Paladin 3/Sorceror X is actually a fairly decent combination. You lose out three levels of spellcasting, in exchange for hit points, Base Attack Bonus, immunity to disease, immunity to fear, smiting, and access to Divine feats-- and the ability to apply your highest stat to all of your saving throws.
Use your one Smite per day for whenever something Evil gets too close to you, or use Divine Might with your (otherwise useless) Turn Undead ability. Since Divine Might requires Power Attack, if you have the opportunity to cast True Strike (an obligatory spell for you), you can Divine Might, full Power Attack, and Smite. That may not drop the monster, but it'll probably be enough to convince it to go back to dancing with your friend, the Tank.
There was also a 2e variant class buried in the Encyclopedia Magica (I think) called the Paramander, which was basically a slightly watered down Paladin, with the full LG and Code of Conduct restrictions, that gained Mage spells.
Monk/Psychic Warrior seems like an intuitive combination to me, and there are a couple Prestige Classes custom-built for this combination-- but, for some reason, they don't combine well with the Monk's unarmed bonuses. I think those PrCs need corrected, but it's a non-issue with my group-- I'm the only player who plays either Monk or Psychic Warrior.
Monk/Paladin is itself an interesting combination, though it isn't particularly effective. If you take a couple levels of Monk (I'd reccomend four, for Lightning Fists), then follow Paladin until you qualify for Sacred Fist, you have an interesting unarmed character-- though it's a very stat-dependent combination.
Monk/Rogue is actually a fairly competent combination, though your unarmed damage and your speed will lag-- but, the Sneak Attack and the additional skills make for an effective skirmisher and ambusher. It's also an easy way into most of the Ninja PrCs, which tend to synergize well with both Monk and Rogue.