somebody should make a software that would bring to units ,camera and handheld gps unit together. i have the gp-e2 for 235.00 it is not a good buy.. it would be nice to have a unit that you could go back to a sight and shot some more.
There are bunches that will merge your GPS tracks from your stand-alone receiver with your photos as (or after) you download. I use Downloader Pro, as I mentioned above. I've also used GPicSync, GeoTag and and GeoSetter for specialized needs. Canon's Map Utility also provides this functionality if you have several cameras and one GP-E2 (or GPS-enabled Canon camera).