I am always looking for new and unique free icons to use in my WordPress theme design and web development work. Although there are a lot of free icons sets available on the Internet, but my favorites are those sets which have icons for almost every aspect of theme design, e.g., categories, tags, comments, RSS feed, e-mail etc.
To save you from the hassle of hunting around on the Internet for icons (free and usable) to use in your projects, I have made a list of my all-time favorite icon sets freely available for download.