By the way, just an FYI, this is my bread and butter right now, as I work for a small web marketing firm called BullseyeLocations which does store and product location software, lead management, location landing pages, etc.
While Google maps doesn't show lat/long lines, you can get the lat/long coordinates of any location by right clicking on the location and selecting "What's Here" from the pop-up menu. The pop-up menu also allows you to select "measure distance" to measure the straight-line "as the crow flies" distance between points.
Interesting, I'll have to check that out. I actually found another site that did very accurate calculations - it was important for testing at the time as we had a client who was bitching about which providers of its services were showing up in a specific search radius.
Pisses me off to no end. I seem to recall a very early version of GM that had the lat/long lines, but haven't seen them in a long time. Have tried searching multiple times and have yet to find a combination of roadmaps and lat/long lines. Best I've found is Goggle Earth has a version of satellite maps with lat/long lines, but not the highways.
I'll have to check at work: I ran across a site that had that some time back, I know I have it bookmarked somewhere. Too bad a lot of the independent sites either drifted away or got snapped up by the big boys. Similar with geocoding software/web services - Google's been dominating the market recently, and, surprise, surprise, once the competition was eliminated they decided to start charging for their formerly free service, and threatening those who didn't comply.