Since Lego does not release any other Mindstorms sets besides for the main one (and the educators resource kit) the main source of parts for NXT bots are the regular Technic sets. All of the recent sets use mostly studless pieces and have lots of good gears, beams and other various pieces that compliment the base NXT set well. For 2008 Lego is going to have three new sets that should be out sometime in the fall. The one pictured will be the flagship set of the year, a sort of off-road jeep. It's got some Power Functions bits, including a new light brick. The power is used to raise and lower the front suspension, which I find a bit lame. The set seems a bit week overall, especially as the top set for 2008. Lego seems to be releasing a real flagship set every two years (the bulldozer in '07 and the Mobile crane in '05), giving plenty of time for folks to save up their money for them.
The other two sets are more interesting, mostly because they include a very interesting new piece! Lego seems happy to have killed the Pneumatics (which were probably very expensive) and have come up with a very interesting replacement that they are calling 'Linear Actuators'. It looks to be a sort of screw in a housing with a universal joint on the bottom. They mimic the look of the pneumatic cylinders (which in turn mimicked the look of real hydraulic cylinders) and serve a similar function. Hopefully they will be sturdy, and provide good power, but without seeing them there is no way to tell. You get one Linear Actuator in the Telehander set, and two in the excavator. The excavator looks to be the go to set of the year, as it includes not only the actuators, but also the always useful treads.
Check out all the pictures over at the Eurobricks forum
