I'm exactly 4.562 feet from the wall
Want a cheap webcam based laser range finder? Todd Danko did and build two different applications to do it. One is in Visual Basic 6 and the other is in Visual C++. Todd based his application off the UB Robotics project. Using some of the examples from Coding 4 Fun, I bet a .Net port shouldn't be too hard. Hackaday mentions a an alternative to the video OCX plugin also. Seattle Robotic Society also has a nice variation of this.
Throw a few these on and get a DARPA Urban driving contender.