I use the same technique as TrainedMonkey and it has worked really well for me.

I actually have a great dislike for the rote memorization of multiplication tables. During school I had everything up to 12 * 12 burned into my brain, but it was as words rather than numbers and wholly sequential. So, when asked 7 * 8 I would have to run through the whole thing up to that point in my mind - "seven times one is one, seven times two is fourteen, ..., seven times eight is fiftysix" - before I reached the answer and could speak "fiftysix" to show I knew it.