SPOT Trackers
All FLARM-equipped gliders in range of the receivers are here: http://live.glidernet.org.
List of known stalkable SOSA pilots:
Rob Russell: LiveTrack24 | SkyLines
List of known stalkable other pilots:
If you have a SPOT, InReach or use Google Latitude on an Android cellphone, and you'd like to be listed on this page, please let me know.
A much larger list is available at http://www.ssa.org/SailplaneLocator.