Today's current gaming portables are starting to look a little old. The DS and DSi aren't exactly high-powered systems, and the PSP is still trying to figure out exactly which form and niche is right for it.
Instead, would you like to play Metroid Prime or Zelda: Wind Waker while on the go? Then perhaps you wish that you had (or had the skills to make) something like this:
Check out this forum thread for more details. Amazing work!