If you don't want to be reliant on (or still don't really like using) a trackpad, and tire of dragging a full-sized mouse around, then the Odin, a laser-projected mouse, might be worth a look. You've seen (even very recently) laser projected interfaces that cover keyboards, but the team that made Odin says it's the world's first laser-projected mouse interface. Which sounds pretty cool... as long as you're willing to carry around the disembodied head of a tiny Transformer when meddling with spreadsheets. We just gave it a cursory web browsing test, and while it lacks, obviously, the physical feedback of either mice or clickable trackpads, it behaves a whole lot the former. We just wished it looked a little, well, subtle.
The Odin moused started life as a Kickstarter project, and it's surpassed its goals and is set to go into full production next month. (You can still order one from its crowdfunding page.) The team says that the lower wrist angle reduces carpal tunnel, and it certainly feels gentler than a physical mouse: latency was decent and the device requires a flat surface to work, with the workable area fixed at just over three inches squared. Limitation-wise, that area can't be changed and while laser projection is only in red, you'll be able to choose from three different colors of robotic shrunken heads. Hit up the crowdfunding site for all the details.