NetMon Cellular Network Monitor for Maemo. Displays Signal Strength in dBm, Cell ID, LAC, RNC, Network Code, etc.
Roadrunner alerts You about speed cameras.
The Snuggle application uses the cell tower information to locate the geolocation coordinates. It captures the CellID parameters (available from the connected GSM network) and by using Google APIs translates those to locate your position in a map.
Seems like an distributed drawing app for the n800 / maemo