Alternativeto - Find alternative Software

This is a useful site, if you need alternatives to software you already know.
For example you want a free alternative to existing software you don't want to use because it is crap and/or cannot afford, then this site will give you a list of alternatives, which can also be filtered after operating system and if they should be commercial, free or free and open source. The rating system gives you also a good hint on which programs are good, look for programs with many ratings first.