Hi,
There is a mobile app called CellMapper. I’ve been running it on an Android phone. It shows tower locations on a map, along with your location, and it draws a line from your location to the tower on which your phone is registered.
You can specify which provider’s towers you want to see (e.g. ATT) and, of course, it can only show which tower you’re registered on if the map is presenting the provider your phone uses.
The app shows its best estimate of the region covered by each cell. It provides lots of information about cells (MCC, MNC, LAC, eNodeB ID, physical cell id, etc. While it does show the tower location on its map, it does not present the lat/lon of the tower.
There is also a web-version of CellMapper (cellmapper.net), but the mobile app is much easier to use.
For my purposes, CellMapper is more useful than OpenCellID, but CellMapper prohibits commercial use, and does not make any of their data available for download.
-Matt