Just this week, we announced a laser option for our CoroBot and Explorer robots.  Planar laser range finders are amazing sensors.  They're more accurate than lasers and infrared sensors, and give higher resolution.  The trade off is that they're more expensive, but the first time you work with one, you'll probably decide that it's worth it.  

When you buy a CoroBot with this option, we will attach an indoor Hokuyo laser range finder - the URG-04LX-UG01 model - in the front of the robot between the two mounting decks.  If you buy an Explorer with the laser, you will get the choice of the indoor URG-04LX-UG01 model, or the outdoor UTM-30LX model.  In both cases, we'll provide the drivers for the robot.  We have also upgraded the software that we provide with our robots.  In Linux, the Player drivers now expose a laser device, and the sample teleoperation application now displays the laser readings.  In fact, adding the laser allows you to use Player's localization, obstacle avoidance, and navigation drivers.  We have upgraded the Windows C language API to expose the laser readings too.  As always, we provide all the source code.