Homemade caramelized onion dip.

Deviled eggs, numerous ways- curry, blt, lox and cream cheese, etc.

Homemade hummus and babaganouj.

+1 for devilled eggs. They are super easy to make in bulk, look super fancy, they need to make a comeback, and they let you be totally creative with the flavours and presentation. Super fancy points: crack but don't peel the eggs and dip in food colouring for a bit. You get a really neat result on the whites.

Get a half cup of cream cheese out to soften and start cooking a very thinly sliced onion in a few Tb of butter or oil, enough to coat a decent sized skillet, on low heat. Stir periodically for about 45 minutes. You can add some chopped garlic near the end, but don't let it burn.

Mix the onions and cream cheese with a half cup of sour cream, a half cup of mayo, and salt and pepper to taste. Some cayenne or paprika or both. I add parsley and dill, but you can use whatever herbs you want. If you really like onion, you can use more.

This is also good with sauteed and chopped spinach and/or marinated artichokes mixed in.

Edit: a dash of Worcestershire sauce, too.