Well, ok, this is a guitar lesson, but nevertheless it can help bouzouki players to strenghten the fingers of the left hand. Justin Sandercoe is the guitarist of Katie Melua's band. He's got a fine website where you can lots of information and tutorials about playing the guitar. There are some lessons which might be useful for players of the bouzuoki as well have a look, if you like at:
Here's the direct link to the pdf file for this lesson:
Another Lesson: The Spider
Here's the direct link to the pdf:
Scale Picking, another lesson:
Here's the pdf:
This is a video I really enjoyed: The rolling technique:
The pdf isn't finished, yet, so we have to wait a while for this.
I think this site is really useful, not only for guitarists but also for everyone who is playing a stringed instrument. So have a look at it.