The feedback I've received from users is that PaisaTours.com is Colombia's best online travel guide. I can't find any other decent Colombia travel guide online (Poorbuthappy is good but does have it's flaws) - that's why I started this website in November 2007. As of April 2008, PaisaTours.com is getting about 150 visitors per day - and that's before I've properly started to search engine optimize the site for search engine rankings.
If you have a hotel, with it's own website, and it's not listed already on paisatours, let me know and I'll probably add it - for free. I expect the adverts and links to remain free until at least 2009, from when there may be a fee. As this site is so young, for now advertising costs nothing. A link back to this site would be appreciated though - use the text "Travel to Colombia" or something similar.
If you are a tour operator, or offer similar tourism related services - get in touch and we might be able to figure something out.
If you want to contact me about advertising on this site, try emailing chris ~ @ ~ paisatours.com, or alternatively webmaster ~ @ ~ bigtravelweb.com (I check the latters emails more frequently) - remove the ~'s .