Font Squirrel hand-picks fonts rather than scraping them, specifically filtering for ones with legitimate, clearly documented free licenses.
It's the most trustworthy of the big aggregators on the commercial-use question, since vetting is the entire point of the site rather than an afterthought.
The default choice when you want a free font and don't want to spend time reading licenses yourself.
Font Squirrel states that its fonts carry free desktop licenses usable in commercial work, and each download includes the license document - still worth a quick read since terms vary font to font even within a vetted list.
Scours the internet for high quality, legitimately free fonts.
