Well, the signal meter and GPS happen to be available to anyone with a suitable mobile phone (which seems to mean Android right now, with occasional support for iPhone) so that leaves a choice of which app to use and which data mapping service to use (the two choices are married, at least for now).
Open Signal looked interesting with their pretty heatmaps and slick application. I had been hindered in running this type of app before this weekend due to a bug in Samsung's GingerBread code for the I9100 Galaxy S2 phone.
Anyway, after loading JellyBean XWLS8 the apps seemed to be able to determine the current cellular signal strength on demand and the GPS was feeling snappy, I decided to trial a couple.
Looking at the various offerings, only two that I found seemed to cover the UK reasonably.
Open Signal do have pretty maps and a very sleek app. Only problem is that, after driving around last night with the app running and visually confirming that it was saving and uploading data, I find that data not present a whole 24 hours later on their maps.
Sensorly, whilst not being so flashy on the maps front, though the app is pretty swish, had my data up on the maps within an hour. I know this because I drove around some pretty obscure country lanes taking the long route back from the dump this afternoon. Those roads had no signal data before I went driving. None of the roads off the lanes I drove around currently have any data either, which is not surprising as we're pretty much in the styx here.
So that's it. Sorry Open Signal map guys - I know it's a free service and all (although you must be spinning it for some fame or ad revenue) but if you expect me to go out of my way and do some tracking, at least be bothered to process my data in a timely fashion.
Seems it's not just me - the forums are full of people wondering if their contribution will ever make it online.
So, in short, support Sensorly, at least if you're in the UK.