Gonna shamelessly self-plug me own book here - Rough Guide Ibiza and Formentera - edition 2 is just out. We've included full clubbing background, but also included detailed coverage of Ibizan history, hikes, secret cove beaches and over 100 bar and restaurant reviews. Runs to 400 pages. Above all, we hope to get you off the beaten track if you crave a bit of adventure. There are so many beaut isolated places in Ibiza.
About 4 years ago there were five Ibiza mags. All have folded except DJ Mag (which was always the best anyway). However, look out for a new Pacha mag, available in the island from mid-June. There will be four editions this summer - it's edited by Ben Turner (ex-chief at Muzik) so content will be decent.
Dub magazine, though badly translated into English, is also worth a read - it's free, you can get it in places like Sunset in Ibiza Town or Particular in Cala Jondal.