Let's say I own a bunch of URLs that are great for my niche (generic, relevant words for URLs). Would it be better to 301 redirect them to my website, or to create a 1 page site with unique content and links to specific areas of my site, including the homepage? If it's the latter, would it be to my advantage to host these 1-page websites on a free web hosting service, so that the backlinks have more weight (they're not coming the same server/IP)?
I think search engines could spot the difference between a 301 redirect and a html backlink. I would agree with the "being on diferent IP's" bit. engines would spot that too and it wouldnt be as affective
Do you think the 1-page idea would be better for SEO purposes, though? Some of the URLs might be showing up as SERP's for phrases (since most of them are short phrases)
I have never actually tried this but what I would try it as you described. This way you can make each 1-page site slightly different (or even completely different) for each keyword you want to target. I'm not sure I would use free hosting though, I have a feeling search engines would know the IP's of free servers and know there lots of naff web pages on them, I have no proof of that though or of what effect it might have on your site. There are lots of 1 dollar hosting sites available anyway just go to www.webhostingtalk.com. get hosting in different countries if you can. The problem with your idea is if you create 20 sites that link to your main site you have to get all 20 promoted well enough for them to have any sort of affect, which could be costly.