What are some good dips for carrot sticks and celery sticks?

I'm having a dinner party on Wednesday evening and for my vegetarian friends, I'm having a variety of things, including carrot + celery sticks. Anyone have any links to recipes for a decent dip?
thnx! =D
Update: needs to be simple so I can make it very quickly please! (preferably less than 20-30 mins)
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