Google Fonts
Google Fonts provides a wide range of free fonts that can be easily and quickly installed on websites through downloads or links to Google's CDN.
dafont
dafont offers a collection of fonts that are either freeware, shareware, demo versions, or public domain, belonging to their respective authors.
Fontshare
Fontshare is a service that offers a growing collection of professional-grade fonts that are completely free for personal and commercial use.