Here's one I like messing around with:
First you should have a whammy. It's not absolutly needed because you can bend the strings behind the nut, but the whammy will give you more range.
Turn your guitar volume all the way down then play open harmonics on the following frets:

E -|----------------------12^--|
B -|------------------7^-------|
G -|--------------5^-----------|
D -|----------5^---------------|
A -|------4^-------------------|
E -|--4^-----------------------|

Quickly raise the volume with your fret hand while simultaneously lifting up on the whammy bar.
If you have a nice beefy sound coming from the amp, this trick should sound like an elephant.
If you don't have a beefy sound most likely it will sound like a sick elephant :-)

Hope ya like it.

A lot of people have guitars with locking tremolos. Some of them get into a lot of stress, because they don't know exactly how it works.

Let me enlighten you on this subject.

Floyd Rose style tremolos work great once you installed the strings and tuned them. They never go out of tune and don't break as fast as with normal tremolos. I use an Ibanez Lo-Pro edge and its really great! When you change the strings, do it like this: First remove the 1st string and put on the new one. Tune it to pitch and stretch a little with the whammy bar.
Then go to the next string and repeat the process for every string.
When you're finished, the strings are all in or nearly in tune, and more importantly they are pre-streched. Tune your guitar one last time if necessary, and then tighten the nut-lock.

(I don't use this technique myself, because I always clean the neck when I replace strings. But for those of you that are desperate, it should work fine.).

You have to use an (auto)chromatic tuner, though. Otherwise it's very difficult to get each string exactly to pitch.

As for the bridge screwing up:

Thats because the bridge is kept in balance with springs at the back of the guitar. If you use a heavier guage of strings, the tension on the strings is higher. This causes the brigde to be pulled up and thus the saddles to be raised, resulting in higher action. It can be compensated by placing an extra spring under the bridge at the back of the guitar and/or adjusting the plate which holds the springs at the neck-end by tightening/loosening the screws.

Once you get the hang of it, you'll see that a Floyd rose is really great. That's why nearly all great rock guitarist have one.

Let's talk about controlled feedback this time.

First of all, feedback works best with humbuckers. They are more sensitive to the vibration of the strings, which is caused by the sound returned by the speaker. This

Use a lot of distortion to get a nice, round and full tone.
If you're not at gig volume, use a compressor to boost the low input from the feedback a little. Put in in front of your distortion.
Experiment with the compressor until you can sustain a note indefinetely. Then you can walk around and find all sorts of spots giving different harmonics.
Every note has its own spot in the room. Try and find them.
Never have the amp too loud, or it will be uncontrollable. Joe Satriani recommends a stage level of about 100 db for feedback. Then you won't need a compressor.

It's all about experimenting, really. If you want to use feedback live, do a soundcheck to find the spot you want. Then mark it with tape on the floor or something.
You can use this in the studio too, ofcourse. But remember to tell the cleaning crew, or else they may remove the tape from the floor, and you have to start all over again the next day.

Happy experimenting!

Play open harmonics on the following frets (use distortion for best results):

E -|--<7>---|
B -|--<5>---|
G -|--<4>---|
D -|--------|
A -|--------|
E -|--------|

Then dive down with the whammy bar slowly. It goes from one clean harmonic to chaos. Very cool!

The next time you change strings, get a pencil and use it on the nut and bridge. This leaves a small graphite coating which lubricates the strings. The strings will tune better and return to pitch better when you're bending or using your whammy.

For great strings, try the Maxima Gold ones for a change. They may bit a bit more expensive, but they have a much longer life and a sound to die for. I've tried them once, and I'm hooked.

If you think they're too expensive, or you've tried them and just don't like 'em, then go for the best quality strings: D'Addario.
I love the sustain and great intonation the XL's deliver. And their phosphor-bronze acoustic strings are the best! (Well they should be, 'cause they invented them).

Try jamming along with your favourite songs, or with songs on the radio. Try to reproduce the style of playing in the song. This exercise will make you a more versatile player.

Recording yourself can also improve your playing. If you listen to yourself, you'll discover shortcomings in your playing and you can work on them.

Get hold of a multitrack recorder if you can (borrow or buy one), and record a chord progression of your own. Jam along with it and you'll see how much better you play when you set your own groove. Be bold and try to fit in every technique you can. Play both fast and slow parts.

Click here for a jam of my own