In your opinion what have you found the best results with as far as SEO goes in regards to semi related content? What I do know is.

-Sub domains are great if you have alot of unrelated content.
For example adult.domain.tdl and internetbusiness.domain.tdl

Since porn and internet business don't mix too well it's obvious to make a division so they are not indexed together.

However which would be better if say you have alot of internet business related content? With semi related topics like marketing, blogging, and ppc

Would you be better off with a normal wordpress installation and just separate the topics by category, or create a WPMU installation and separate those topics into sparate sub directiry sites?

All comments and opinions welcome, verbose explainations preffered.

The title of your post is a little misleading. You can easily run blogs with different TLD on single install of WPMU, so the question is, what structure is better?

I am of opinion that the best option is to have a separate TLD for each keyword, but if that's not possible, then sub-domains would be the next best thing for unrelated keywords, and topics/categories for related keywords.

I imagine, it will also depend on the quantity of content. If you create a sub-domain for one of your business niches, will there be enough content to justify a separate domain?

Hmm never looked at it that way.. Yes I suppose after some time there would be enough content at justify a subdomain.. But just starting out would a directory be better?

Gotta disagree with futurer re. subdomains. From a Google/SEO point of view all links that come into a single TLD count towards the positioning of any one single page in the SERPs (site links as opposed to page links, although obviously inbound page links are the first priority). So, subdirectories will always be preferrable to subdomains as ALL incoming links to the site will count.

As to categories v. subdirectories, from the first post, it actually doesn't matter if you're using a subdirectory format in WPMU, or a category in WP, as the URL string can/will look the same. The only real advantage of using WPMU is individual subject theming, access control etc.

Has anyone here been successful with autoblogging with WPMU? I mean making from Adsense and not just using MU for a blog farm linking.

Originally Posted by freller

The only real advantage of using WPMU is individual subject theming, access control etc.

you make a very good point there.

So would it be safe to assume in many cases if you're using ad sense or something of the like you'd be better off with WPMU because you can theme the site accordingly, making it look better and potentially getting more hits.

Where as if using affliate marketing you'd be better choosing a single product that you know people are looking to buy. And use a single wp install, automate content, have the content accumualte in the background for SEO reasons and send readers to a sales page for the specific product they are looking for.