Best/Most Fun Exercise

Well, in the world of technical exercises, most are just boring. I've gotten quite tired of going up and down the chromatic scale, or going up and down in modes one note at a time, in groups of three, 1, 3, 2, 4, 3, 5, groups of four, etc. and I'm looking for some new ideas. The main thing I'm looking to develop currently is good alternate picking. I can play 180+ bpm 16ths legato, but when I'm alternate picking I can only do 100-120 and stay in time.

One exercise that's not incredibly boring (yet) is to play all the modes, 6th string root, 3 notes per string patterns up and down the fretboard, but it's starting to get old.

I like the intro riff to Malmsteen's "Deja Vu". It's pretty straight alternate picking at first, but it's a bit tricky when it starts to pedal.

What're your favorite exercises (or riffs) to play, and what do they develop?

I used to spend hours practicing the trick below just going up the fretboard, I've never been able to do it at a decent speed going back down.
It's a total beast, I like the idea of pulling off onto a natural harmonic and then playing with pinch harmonics so your hands don't have to jump up the fretboard.

http://www.guitartricks.com/2000/trick.php?trick_id=4266

Hey Andrew, could you post a soundfile of you playing (or trying to play) the exercise you pointed me to?

Hi there Mr Mud! I can't post a soundfile at the moment. I'm using a university computer account belonging to a friend of mine who was a member of staff for a while before he went elsewhere. My own computer is unwell and not currently internet compatible anyway (my modem is 200 miles away..). I might get to record it on a friend's computer but I really don't know when.
If you're struggling to find the notes in the meantime (the notes those harmonics are supposed to make may not be clear) just bear in mind that the whole exercise is just an extension i.e. note, miss note, note etc and it's all in the key of Cmajor. I'd right the notes but I honestly don't know them and don't have a guitar with me.
On my flatmates fender strat the first pinch harmonic falls slightly neckwards (3-4 mm maybe)from the middle pick up and is caught on an upstroke after you pull off onto that 7th fret natural harmonic. This saves leaping your hand around. The next harmonics fall about the same distance from the middle pickup but towards the bridge. The final harmonic is slightly nearer to the pole peice of the pickup than the previous 3 and not so quite so close to the bridge (mm?). The last harmonic is really hard to get, it took me a lot of training to get anywhere with this run. You'll want tons of gain, maybe compression and a whole lot of patience.
Good luck my friend!