Continuing the Alesis tradition of high quality cheap music gear, the MMT-8 is a very popular hardware sequencer for MIDI intruments, which at the time of writing you can pick up for around £50-100. It is an eight-track MIDI signal recorder capable of storing 20000 events, such as notes or controller changes. Like any device it has its strengths and weaknesses, but overall its advantages far outweigh its failures.
On the plus side, it is immensely portable, weighing very little and being reasonably small. It is also very good for live work, as it enables the user to loop any part, which could be anything from a 2 beat break to a full 64 beat note sequence. This means you can be very dynamic on stage, adjusting the songs to suit the crowd or yourself! A testament to its on-stage quality is the fact that Orbital use three of them to drive their equipment during live shows.
One of its problems I mentioned before, which is its low memory. Without purchasing a data storage device (such as the Alesis Data Disk - around £140 second hand) you can't store an awful lot on there. In fact, mine is almost full, and I've only got about an hour and a half's music on it. Admittedly, this is fairly complex stuff, but nevertheless, it is extremely frustrating to get the annoying
BUMBER DUDE, OUT OF MEMORY!message. I shall be buying another one soon in order to use one to control the other. In this way I'll be able to run different length parts on each machine simultaneously, so that I can match, for example, a 24 beat bass sequence with a 32 beat drum and lead part. Using the internal sequencer on the drum machine I can drive a 20 beat drum part so that the overall effect is very varied.
Another down side is its controller support. Some devices (particularly early implementations of MIDI) require controller signals which the MMT-8 just won't send. This is not a great problem, but it did frustrate for a while.
On balance it is extremely easy to use, fairly versatile, cheap and easy to carry around. It requires no time to boot up, backs up to tape or disk, can control almost any MIDI device, and is a very good value for money purchase.