if you own a web host - then start an affiliate program... free advertising... apart from that I have no idea and little success
Yeah web master forums would be a great place to start. If you can offer a better price than most and still provide good service then you should not have a problem at all. I got some hosting on ebay for like $10 for life and the servers are pretty good IMO. I can sell it at $1 and be good but why lol. Try finding one that is good and cheap and offer a year service for a really good deal.
You could write some sort of useful guide, such as how to set up a website, and include links to web hosts you are affiliated with.
GO to http://www.hostome.com/ and buy unlimited server space from them and resell that space according to your terms.Their high performance plans with suitable solution,you must give them a try.
you can add it in web hosting directories, write hosting reviews, submit to hosting comparison sites..etc
The best-performing way to market webhosting I've seen thus far is with review sites. I actually created and tested several lead generation campaigns a while back for web hosting. They weren't successful as it appears that web hosting can fall under the "considered purchase" category. Individuals looking for such services take their time to select the right one; thus the "consideration". This niche is still worthwhile pursuing because of the high payouts though.
You could find web hosting related blogs, and leave useful comments on them with a link to your site, ensure that the comments are useful or else they could be removed by the admin