None of it is any big deal. You can delete the first three plists. The first is just some Yahoo installer, the second is just the mactracker app, the third is for the iPhoto screen saver option. Empty the trash after deleting them. If it says any are in use, log out and back in.

The last plist though is buried in the TechTracker preference pane. Uninstalling then reinstalling it may fix it, if not it's just a bug in the preference pane.

None of it should cause problems with the Mac except maybe the iphotomosaic.plist since it's for the iPhoto screen saver. In worst case it would just crash the screensaver probably.