You can buy aftermarket "diamond cut" multisurface reflector type replacement lamps instead of the fluted lens factory type, which in some cases seem to give more light since they are more efficient.
There are also projector-type housing assemblies available, though quite costly, and even kits that claim to allow HID to be used.
The factory lenses are probably the best bet for general all-around use though, and you can just upgrade the bulbs with something like Sylvania XtraVisions or Philips Hi-Visibility or Vision Plus, which will give more light on the road than standard bulbs and aren't too costly.
Search around on the lighting forum and you can get more info on these and other similar upgrades, and decide what you're looking to do and what will work best for you.