As a Wizard, I'm mindful that there are four feats I demand for myself if I am to be able to remain versatile in a panic situation: Quicken Spell, Silent Spell, Still Spell, and Eschew Materials. They're all in the PHB, and easy to acquire with moderate speed early in the campaign. You'll find that with them, there isn't a situation out of which you can't successfully think yourself. With that said, let's consider some good spells that will make it easier for you to escape a grapple, eh?
Level 0
Flare is a good way to dazzle a grappler. Close your eyes before you cast it. ~_^
Touch of Fatigue is a good way to give them a minus to their grapple, and since they were stupid enough to initiate physical contact with you, you don't have to work too hard to succeed the touch attack!
Level 1
Grease has been mentioned and is fun for rp if you don't mind taking some minuses yourself. At least you won't be grappled.
Charm Person is a gamble, but if it's successful, it'll turn that angry grapple into a friendly, brief hug.
Hypnotism is along the same train of thought as Charm Person, but it's a little more effective in combat (if only marginally).
Color Spray will not only do the trick with flare and style, but you'll give yourself and your buddies a tactical advantage.
Cause Fear is a superb method if your target has </= 5HD.
Reduce Person is by far the most entertaining way to get free of a grapple (whether cast on you or your grappler), especially if you Quickened a Grease right before it. Your party may hate you, but good grief, it's funny to do.
Those are some great level 0 and 1 spell suggestions right off the PHB lists. Make sure your spell selection is ideal to the targets you're fighting. Good luck with that grapple! Always remember: a Wizard is never out of options if he keeps his head clear. Defeat is an illusion borne of the idea that one is otherwise out of ideas.
