With the holiday weekend coming up in the U.S., avid divers may be making their way to their favorite spots. Dive.io is a web service designed for divers, so they can log their dives, share their favorite dive spots, and meet fellow divers. It's very specific, but it does its task quite well. It also has a nice API, allowing for integration of the service into, well, anything at all.
There have been a lot of new socially based mashups showing up recently. In fact, we recently topped 700 social mashups. While many of these use the Facebook API or Twitter API, there are many more social APIs. The mashups below run the gamut, though, yes, also include Facebook.