I just pretty much finished another MIDI sequencer project, using the Akai MIDI Mix USB controller, in preparation of a live show I'm playing in October with VLK.
It's a drum sequencer for the Audiothingies DoubleDrummer, which I plan to load up with some fun percussion samples. The Axoloti sequencer can play six voices and for each voice, I can send even clock division triggers (/32, /16, /8, etc.) and "uneven" ones (just a bunch of custom divisions I like), based on a generated MIDI clock. I can also shift each voice's pattern, so that it doesn't overlap exactly with another sound, or plays between beats. On top of this (or actually below 
), there is a fader which sets the chance for a random trigger to be sent to the voice on any MIDI clock pulse. This can be very off-beat, so I also programmed the right-most fader to quantize all triggers of all voices into even beats - again by using clock divisions like /2, /4, /8, /16, etc. The regular triggers and random triggers can be muted separately for each voice with the push of a button. Additionally, there's a chance-based sample randomizer which can load a different sample into a voice and I can control the DoubleDrummer's built-in master LPF, Crusher and Reverb.
This lets me create a very wide variety of rhythms quickly, by simply turning a bunch of knobs and depending on the master quantizer and random trigger chances, I can make sure that nothing bad happens ... or just a little bit ... or a whole lot of messed up rhythms 
On a different MIDI channel, there is also a random CC20 value being generated as well as a random (but lockable) melody, based on certain trigger combinations. I use this to add some additional (semi-)randomness to my AE Modular synth, which will also be part of the show, and which has a built-in MIDI-CV interface.
Here's a quick demo video:
... and pictures:
Cheap and lots of controls, plus LEDs which you can turn on and off by simply sending it certain MIDI notes.