the answer you're most likley to get is have a search! There's loads of things you can do depending on how much you want to spend but most of them are not cheap!
People tend to sort the handling out first with some strut braces/ARB's and some coilovers then if they're certifiable they go on to engine mods
chris has supercharged his 1.8 16v
F2stu has an insane ABF cordy
there was a lad with an 8v and a good shot of NOS up it
and dinkydave is up to about 190bhp
other than that there's the old VR6 or 1.8t conversions that are kicking about.
I'm being far too helpfull for this time in the morning, have a search