Most of the free software I come across is actually found with 2 resources. PC Magazine will send out email daily that features any new free programs but there is a lot of tech industry news that might not be of interest. A list of the editor's favourites came through today and is quite extensive, click here for a look.
The other source also lists new and useful webpages. Appsource is also a PC Mag site so you may see the same thing more than once, click here for a link.