AlternativeTo (http://alternativeto.net/) is a MUST HAVE in your in web toolkit.
Especially in today's economy, one can't shell out the $699 for a shinny new version of Photoshop. Don't get me wrong, I love Adobe Photoshop and I own several versions back (Creative Suite 2 for Windows), but I was looking for "AlternativesTo" Photoshop on the Mac. The keyword being "Alternatives".
This is where http://alternativeto.net/ comes in. In my example, I was looking for an Alternative to Adobe Photoshop on the Mac.
The first alternative in the list is GIMP. GIMP may not be as polished as Photoshop, but for the price of $0, it can't be beat. It gives a description, alternatives and links to the website.
AlternativeTo uses a social promoting method that allows the good alternatives to rise to the top.
AlternativeTo is a site that I keep coming back to time and time again.
Hope you get as much use out of it as I do.