Hotfrog - if you're outside the USA, check their International sites link at the top right
Search for "business directory" and you'll get a bunch of listings. Just stick to the free options as the goal here is to simply get a link.
Local Listings - if your organisation services a local area, you can list in Google Places and Yahoo Local. Also check if there is a specialist local site in your area.
News Sharing Sites - such as Digg, Mixx, Reddit
Bookmarking sites - Delicious, Mr Wong
Article sites - write an article related to your industry and include a link to your website - Ezine Articles, HubPages, Squidoo
If you follow the above steps, your site will get indexed much faster.