Using core, you could do a Fighter/Wizard/Eldritch Knight, I believe that's one of the new prestiges in the 3.5 DMG.
I wouldn't advise a Druid or Ranger/Wizard or Sorcerer. Using a hybrid druid/fighter and a full arcane caster would result in too many skills, not enough focus. You'd need to have a lot of good stats too. Good Int for the Wizard, good Dex for the Ranger, and probably good Str and Con too. You'd also need Wis if you wanted to spellcast as the Ranger.