Download.com
www.download.com
Download.com is the most comprehensive software websites that I have came across. they offer software for both PC and Mac and it is catagorised by genre (audio software, utilities, Antivirus etc). If you are looking for software to do a particular job you can search the entire database by keyword, once you have your results you can sort them into date or alphabetical order or you can narrow the search by platform, catagory or you can filter the free software from the commercial.
The great thing about Download.com is that you can trust all of the software listed on it to be free from viruses. So if you are looking for a new piece of software or if you know the name of the software you want, saerch for it on Download.com and rest assured that if its on there it will be save to download and instal.