I need help here, if I want to sell more then one affiliate programs, should I separate them out in different domains? Anyone had done this before? Please help. Thanks
Well, it depends. Most affiliate programs SHOULD give you links for promoting. In that case, all you need to do is cloak it with a free domain like Dot.tk If you need to host a page yourself, and your main source of traffic is SEO, then yes, space them out over domains. If not, and you are doing bum marketing or something, then you shouldn't need to, just put them on one space and cloak the exact page URL with a free domain.
If you are talking about landing pages, yes, you should have separate domains for different products. Your landing page should direct the attention of the reader on a single product you are promoting and you shouldn't try to do too many things on a single page.