If you recognize the name Usenet, you've probably been on the internet for a l-o-o-o-o-n-g time. Usenet has been around since 1979, tying people together in little (or not so little) electronic clubhouses.
But even if the name doesn't ring a bell, Usenet gave rise to what are now known more generally as Groups. Groups are sort of like forums (which you're probably familiar with) and sort of different. A key thing about Groups, though, is that they're in a separate corner of the internet, and they don't show up in ordinary searches, unless you specifically look for them.
Blue circle for the topic of the Group, red circle for a full text search.
There are groups for just about every topic imaginable (and quite a few that are unimaginable, but we won't go there...). Of course, there are groups for genealogy and family history. Tons of them. Groups in the US, and Groups in the UK. Groups in English, and Groups in Slovak. Groups for medieval genealogy, genealogy in the Azores, and family histories of individual surnames or geographical areas.
But if you want to see what these Groups have to offer, you have to make it a point to go visit them.
So go ahead an explore. Try Google Groups for starters (which includes the Usenet archives way back to the 1980's!). Note that there are two types of searches here -- one on the main topic of the group (the blue circle in the picture to the right) and one that searches the actual content of the posts (red circle). Try them both.
Then take a look at Yahoo Groups, which also has some surprisingly rich content in the family history arena.
By the way, with a quick registration at either Google or Yahoo, you can easily start your own genealogy clubhouse, er, Group on the internet.
Enjoy your exploring.
Visit the main page of Free Genealogy Tools for more, umm, free genealogical tools.
And don't forget to also check for your family history at Ancestry.com and NewspaperArchive.com. These are subscription databases, but they are among the most powerful research tools available for looking into family roots.