I don't have a GPS, but I have been adjusting streets in my local area to match the Yahoo! images, and verify street names from TIGER data. I've also added a few items such as a couple schools, our local library branch, and a couple businesses.
My Local Area is currently Riverton, Wyoming, US.
Lately I've been working on tidying up and adding relations to I-80 through UT and WY, with little bits of random things around the US, like fixing dupe nodes on and around primaries.