I'm a resident of Grays, and have had a GPS for some years which I use for general exploring & Geocaching. I discovered OSM through a Linux User Group which hosted a mapping party.
I joined in early March 2007 & have been working on S.W. Essex, largely Aveley, South Ockendon, Grays & Stanford-Le-Hope until October 2009, as I covered a lot of these places day to day & by simply varying my route have been able to get most roads covered. I also have 2 large dogs, so where you see footpaths you can be fairly confident of being able to take dogs!
In 2009 I moved to the Isle of Wight, where I had already added some paths & POI's and found a couple of roads previously missed.
My GPS traces are a mix of walk / cycle / drive logging. I currently own a Garmin Vista HCx, used to have a Cx (but it's MIA presumed nicked) and an old Vista which went AWOL in 2006 but (amazingly) was returned after a long gap, but doesn't work too well :(
Favourite OSM trick; going to foreign parts with a GPS, containing map of it without the hassle of having to find & buy one. Of course, adding bits if anything's not done :]