Here I found a very useful list of free alternatives to very useful and popular Desktop Software. 1. Word Processing Google Docs: Free online office suite that offers document processing, spreadsheets, even work collaboration. Acrobat: Create PDF files, convert files, and make forms. PDFescape: Free PDF form editor within your browser; can also use it to fill in PDF forms online. OpenOffice: Free open source productivity package that is similar to Microsoft Office. AbiWord: Simple word processing program; multiple people can collaborate on one project. Zoho: A free online word processor that works within your Web browser. Share, collaborate, edit, create. NumSum: Create and share Web spreadsheets. Writer: Simple writing utility meant to encourage concentration and focus. CKEditor: Web-based text editor. NeoOffice: Full office suite for Mac users. 2. Communication Meebo: Centralized dashboard for several different instant messaging programs. TokBox: Live group video chat anywhere, anytime. faxZERO: A free fax tool you can use on your computer (covered more fully in Five Ways to Send a Free Fax Online). Google Voice: A centralized online space for phone calls and voice messages. OoVoo: Free video chat from mobile to mobile, mobile to computer; up to six people at once. eBuddy: Web-based instant messaging that works on any computer; integration of all popular chat programs. Pidgin: Instant messaging plugin for simultaneous chat networks. Trillian: Chat client for computer and phone. 3. Presentations Sliderocket: Easy to use with many of the same features as PowerPoint. Prezi: Create high quality presentations completely online. ScreenCastle: Free screencast recorder you can use to film activity within your browser. Vcasmo: Multimedia presentation tool with a wide variety of interactive features. Empressr: Presentations with photo, music, audio, and video; can embed anywhere on the Web. Animoto: Slideshows from videos and photos. Flixtime: Video slideshows with sophisticated graphics. PhotoPeach: Free slideshow utility. SlideShare: Share your presentations with others. Screenr: Instant screencasts with a Web-based screen recorder. Storify: Make slideshows using social media content. Vuvox: Produce videos using your own multimedia. 4. Security ESET Online Virus Scanner: Finds and removes threats; not intended as a full security suite, but a good option. LastPass: Keeps track of all your passwords in one convenient, secure location. VirusTotal: Identifies suspicious files or URLs. ClamXAV: Free virus scanner for Mac computers. Virscan: Free Web-based file scanner; upload a file and it will scan it for infections. Avira: Free antivirus protection program for home computers. Avast: Free protection against viruses and spyware. AVG Rescue CD: Helps you identify deep-rooted virus/spyware infections and get your computer working again. MalwareBytes: Scans your computer for spyware, malware, and viruses. Microsoft Security Essentials: Free antivirus protection from Microsoft. 5. Image and Video Management and Manipulation Aviary: Similar to Photoshop; all sorts of image manipulation/editing tools here. JayCut: A free online video editor. Splashup: Free image editor and photo manager. SmugMug: Free photo management tool. Vixy: Download videos and convert them into playable formats for your computer. Miro: Converts video files for playback on computers and mobile devices. Talon: Instant screenshot utility; also available as a Google Chrome extension. GIMP: Offers many of the same features as Adobe Photoshop; free image editing program. Pixlr: Online photo editor with menu of advanced effects. Rsizr: Re-sizes images fast. FotoFlexer: Advanced Web-based photo editor. Picnik: Browser-based photo editor with menu of special effects. 6. Organizational Tools Evernote: Jot notes, take pictures, and organize your thoughts and online life in one place. Springpad: Save, organize, and remind yourself with Springpad's easy to use interface. Toodledo: Type in what your day looks like, and Toodledo organizes it into a personalized to-do list. Toggl: Tracks time spent on task so you can more easily bill it. iClippy: Captures data from anything you copy and paste (text, video, images) and puts it in one convenient place. Zootool: Organizes all your Web bookmarks into a searchable index. MyNoteIt: Geared towards students; a great way to organize notes and share with others. Remember the Milk: Management of all online or offline tasks. 7. Calculators, Graphs, and Financial Management Mint: Similar to Quicken, Mint offers one of the most robust financial management dashboards on the market. Instacalc: For any mathematical computation you might need. Includes scientific notations. Gliffy: Create free diagrams, graphs, flowcharts, and technical drawings. Web 2.0 Calc: Scientific calculator with standard functions. Create a Graph: Easy online graphs for simple projects. GnuCash: Free accounting software for home and business use. Hourly Rate Calculator: Helpful for freelancers who are trying to figure out how much to bill clients. Buxfer: Free online money management with an intuitive dashboard. Yodlee: Track spending, pay bills, and control your budget. eCalc: Scientific calculator available online and as a download. 8. File Management, File Sharing, File Conversion, and File Organization WobZip: Unzip compressed files, either from your computer or online. Zamzar: Fantastic tool for file conversion with dozens of file formats available. WebFTPer: Browser-based FTP (file transfer protocol) tool; manage your website files from anywhere with an Internet connection. Movavi: Free file conversion tool that converts multiple files at the same time (limited file size/length). Ubikuo: Storage of online notes available anywhere with an Internet connection. Dropbox: Free file hosting service that allows users to access their files from anywhere. eSnips: Upload, share, or download files, photos, videos, or music. Mediafire: Free hosting and sharing for any file. YouConvertIt: Free file conversion for wide variety of file types. 9. Project Management and Project Collaboration Pirate Pad: Streamlined notepad application that enables anyone anywhere to collaborate on a project in real time. Mindmeister: Free brainstorming tool with collaborative features; free but does include tiered pricing options for more features. Bubbl.us: Highly functional brainstorming tool that can be used in tandem with other people. Mindomo: Collaborative mind-mapping tool; real time sharing and file uploads. Meeting Wizard: Arrange and schedule meetings between multiple people groups. Writeboard: Collaborative web-based text document creator/editor. Vyew: Free real time meetings, collaboration, annotations. 10. Lists, Calendars, and Productivity Tools 30 Boxes: Track birthdays, friends, and tasks with this interactive calendar tool. TaDa List: Web-based list maker; make lists and share lists. Monkey On Your Back: A to-do list for what you would like other people to get done. TimeXChange: Task tracking with time/project features. Todoist: Personal project tracking and management. Tom's Planner: Personal project management via charts. Evernote: Organize your notes, photos, videos, etc. in one place for easy access. LiveBinders: Collect online "resources" and organize them easily. Doodle: Create and manage events for multiple participants. Upcoming: Track event calendars in your local area. Google Calendar: Make multiple calendars, share events, track workflow.