gdivelog is a SCUBA dive logging application for GNOME. Can download Suunto Cobra, Mosquito, Spyder, Stinger, Vyper and Vytec; Sensus Pro; and Citizen Hyper Aqualand. Can import from SmartTrak/DAN DL7 and Suunto Dive Manager 2.
KDiveMaster is a KDE application for SCUBA-divers. It is intended to serve as an electronic dive logbook.
Subsurface is an open source divelog program. Subsurface can track single- and multi-tank dives using air, Nitrox or TriMix. It allows tracking of dive locations including GPS coordinates (which can also conveniently be entered using a map interface), logging of equipment used and names of other divers, and lets users rate dives and provide additional notes.