maybe you have some advice or know some exercise. I have this problem with i-m-a arpeggios The ring finger is just too slow. It's obviously because as I pick with the middle finger, it drags the ring finger with it towards the string and I can barely move the ring finger up until the middle finger is "done". I hope you get what I mean. So I need to get the ring finger get more independent and stronger. Do you know of some exercise other than, well, playing the arpeggios over and over?
It's not exercise you need, its a technique called planting, basically you move the next finger to the string while the other one plays it, you need to practice moving that way, then as for speed the sky's the limit
If you're going to work on planting (and you absolutely should, even if speed isn't your goal, every fingerstyle guitarist, classical or otherwise, should know how to plant), try simply muting with your left hand and focusing completely on your right (or vice-versa if you're a left-handed player, obviously).

Plant all your fingers down on the strings you intend to pluck at the beginning of the arpeggio. For example, place all your P, I, M, and A fingers down on E, G, B, and high E, respectively. Then go through the arpeggio, making sure to keep the fingers coming up next planted as you go through the arpeggio. That is, make sure you are not naturally lifting your M finger back up as you pluck with your I finger, and make sure your A finger stays down as you pluck with the M finger. Practice the arpeggio going P, I, M, A, and repeat.

If you're looking for more concrete practices, try these: http://www.stormthecastle.com/classical_guitar/Collection/120studies-for-right-hand.pdf. I still do these at random during my warm up; they're great to have around to get your playing nice and even. Make sure to do the exercises at a nice easy tempo... somewhere between 40 and 60 bpm. These exercises aren't about speed, they're about precision. The general rule for planting in these exercises is simple: if there's a way to plant your finger ahead of time, do it.

Hope that's helpful.
Thanks guys, I'm working on this! and those Giuliani exercises seem useful!
When I first started practicing my "arpeggios technique" I spent a lot of time getting used to moving up and down the string P I M A I M A ing with open strings. Roughly half an hour in front of the TV everyday until I was really comfortable with it