Along the lines of the Roland amps, but smaller, would be the Mobile Cube. Unlike the Micro Cube, it's a catch-all amp for just about any instrument you want to plug in, since its based on being a keyboard amp. The uke does well on the acoustic setting, or the electric setting if you want that imperfect type sound. But it especially shines in keyboard mode.
And like OldePhart's theory, it's small dual speakers. It's easily the best match to a uke I've yet had, and is a bit cheaper than The Marshalls and Fenders, and AC series type higher end amps... while still not sucking.