I think if you like:
- trance, Cream is the most important. Armada seems to be a good night for trance people. Both take place at Amnesia. I think Timo Maas @ DC10 plays more serious trance.
- techno/electro-techno/minimal. Cocoon @ Amnesia, my favourite party on the island.
- techno/hard techno. I guess Carl Cox @ Space, La Comunidad also at Space and Meganite @ Privilege are your nights.
- Proggy music: Pure Pacha, Yositoshi @ Pacha
- Tribal house/Balearic/tech-house: Matinee @ Space, Balearic People @ Penelope, People From Ibiza @ Amnesia.
- Funky house/latin house: Release Yourself, Defected or Subliminal. All three at Pacha. La Troya @ Amnesia. I'm not sure if Hed Kandi and Miss Moneypenny's @ El Divino are similar, or if it's more US garage.
- Not to miss for everyone who loves wicked and wild parties: We Love Sundays @ Space (the music depends on the DJ and the terrace (funkier)/inside(darker, techy). Circo Loco @ DC10 (even though I have missed it every year

) everybody say it's a must. I'd also add Manumission (if you've never seen it you have to).
- Main gay nights: La Troya@Amnesia, Scandal and Gorgeous @ Penelope.
I miss lots of nights to mention, but I think those are the most important. And maybe I'm wrong in something. Correct me if so. Moreover if you're British and very young, you might love the clubs in San Antonio, Es Paradis and Eden.