Using the Eten M600 with a Globalsat BT-338 bluetooth GPSr.
I havn't decided on all of my software yet but appear to be leaning twords Mapopolis and Beeline GPS.
I create a custom map overlay for Mapopolis that includes all Cache's within 50 miles of my house. I also load the details of those Cache's into Beeline. Last weekend we went out to brekfast and decided to see what caches were around and found 4 that where within a mile of where we were. Since my M600 is also my cell phone with GPRS data, I can log the cache as we find it. I think it would be a great feature to be able to upload my finds directly from within Beeline but I guess I need to wait for software to catch up with the technology.
I've got the technology, now I just need to learn how to actually find the cache without my Wife or son finding them first.