Learn PhotoShop mate - it'll take you years but it is a very rewarding programme that you will never get to the bottom of. I have been using it for about 4 years now and am still finding new stuff out. There are thousands of sig tutes and most of them are for fairly ho-hum, derivative manga/motion blur style sigs. Usually with lots of spikey metal.
It is not necessary to be 1337 at all the uses of filters, masks and blending to make a good sig - the idea and basic layout is prolly more important. For example, in my opinion one of the best sigs I ever made (for originality) was this:
Which is basically one large image cut down with a gradient mask over it (the fadeout on the right) and a funky font I downloaded with a bevel effect on it. Took about 5 minutes.
A good place to start looknig at tutes for sigs is
www.pslover.com but don't get discouraged if your sig doesn't look like you expect at first - remeber that it takes years (mebbe decades) to learn PS properly.
Until you work it out, here's one to be going on with: