I've got a Roland Micro Cube RX for bass.
I use it for home practice. Rehearsals with acoustic bands. Busking (can run on 6AA batteries).
It's never going to move much air, but the useful features it has got are;
An in-built tuner
Several effects (chorus, octave, wah, flanger, delay, reverb.
Aux in
headphones/record out
Metronome
A 'drum machine' - which is several pre-set rhythm styles (e.g. rock, jazz, country, latin)and is quite good fun to use.