Does anyone know anything about radar scanners/detectors? Legality issues: I mean, they sell them at circuit city but I dont know what kind or whateve,r i just now started looking into them. So, do they tell you basically if some police radar is scanning around you? Does anyone have this application and if so can you give any sort of recommendation. It would be useful to know when you need to slow down i guess but Im just wondering how these things work and if they are worth it.