I've looked at a couple of different Sex Offender maps online over the past couple of months and it's generally pretty disheartening and scary when you realize who might be living next door to you.
Over the past couple of years, people like John Walsh have pushed legislators hard to make state lists publicly available. With modern technology, these lists have now been combined with mapping software so you can see where a lot of these pervs live in your area. One of the more recents ones is a mashup combining GoogleMaps with state registries: MapSexOffenders.com. Another more recent startup is The Family Watchdog; I found that one to be even more alarmingly detailed. Here in Washington, you can see the address where they're living and a recent picture and description of the perp. Do check them out yourself and tell your kids to check it out. Yikes!