Originally Posted by CritAnime
But if you can get your hands on a Multi Mega then it would be an extremely nice piece to add to you collection. While on the subject of odd revisions then how about the Nomad.
The MultiMega's pretty cool - Mega CD and Mega Drive in one portable CD player-sized box. The Nomad's trickier. The screen technology, by modern standards, is crap. Poor resolution, blurring, etc. Plus, second-hand units (which are the only ones around now) will have wear and tear that doesn't really affect the non-portable versions. If a MultiMega pad is worn out it's easy to get a replacement. Replacing worn out buttons in a Nomad is much harder.
If you want a portable Mega Drive (and something like the GP2x Wiz or PSP is out because you want real hardware/don't want to give filthy Sony any money, even if you're hacking their console to run homebrew), you could consider one of these:
Both have cartridge slots and are lighter, smaller and more battery-friendly than the Nomad. However, both have mixed reviews due to compatibility issues and build quality.