Hi Nemesis , take a look at commission junction they're pretty good to promote single products. You do need to have a website to use them though because advertisers (people that have stuff you can promote) that use the network have to approve your site first before they allow you to promote their product. However, you don't need to have one to enter the network itself I believe so you can check out what kind of a niche you want to get into before actually making a website to promote it on. If you have the time I would sign up for both CB and CJ so you can check them both out. You will need to do so in the end anyway if you want to spread you earnings. Again, I'm not sure if you also need a website to sign up with them in the first place, can someone confirm this?
Have a look at CPA programs. Just search the forums for a list of CPA comapines.
Some good CPA networks are:
You promote a variety of products, from free trial to email submit offers. Email submits are pretty easy to promote since it costs nothing to the person, the're just entering the email addresses and you get paid for the lead. Lots of info in this forum about CPA networks.