Mine is (*click* aww, still on the lorry) coming. I was going to start with Osmand for the droid / OSM apps, and then play with Vespucci for an editor. Bike Hub uses OSM for bike-route routing.
Google Maps is a no-brainer. OS Atlas Free is a UK Ordnance Survey map eye - no routing, nice for a ramble?
Dude Where's My Droid looks useful (any alternatives?). Mails you back with a GPS fix.
Google Goggles, Wikitude, Google Sky, Word Lens for the augmented-reality wow-factor...
What weather apps do people like? The Weather Channel looks best of the bunch, but only until the Met Office one gets ported from iOS.
AppBrain has a "people in the UK like" filter:
Get the Popular Android apps in the United Kingdom on AppBrain (and other filters too, yay dropdown)
I'm gonna be
hammering the ether with this thing.