This acronym, meaning "birds of a feather" - the idiomatic shortening of the proverb completed by "flock together" - is often used by the Internet Engineering Task Force (IETF), to tag meetings of interest to particular groups. As is the case with migrating Snow Geese, engineering specialist do tend to flock together.
Recently, a like-minded bunch of high-flying coders in Palo Alto released a new browser built specifically to support communities of web-users who share common, and often collaborative, interests. Flock, available free to the public with version 0.7, is built more for connecting than for browsing. It makes sharing photos, managing news feeds, updating blogs, and searching for stuff easier than ever.
It's fast and, so far on the Bent's G5, stable. Perhaps the coolest feature is the real-time search box. Just begin typing and a pull-down opens and BoF results, from search engines, recent searches, and your own favorites, all flock together.