Pack away all the special toys your child is particularly territorial over. Also, don’t unwrap gifts at the party – all will want to play with them, but birthday boy won’t want to share. Avoid the fight altogether.

Keep the guest list small for 3 and under, they get too overwhelmed with too many faces. Also make small cupcakes as opposed to making a big cake. The kids can’t compare the size of the pieces and they get less sugar.

YES to the suggestions already posted!
Also….keep the party shorter than you think you should! Try to take a picture of your child with each of their little friends so you can make a quick personalized thank you.
One more thing….have a glass of wine, a bubble bath, a night out or anything else planned for YOU to enjoy after the festivities. You deserve it!

I know this is a delayed answer and may not be helpful to the original question but hopefully someone else will be able to use the ideas.
I would recommend having more activities planned than you think would be necessary as any free time is a recipe for craziness.
- Plan a craft (that can last at least 10 minutes) and cover your table with a good plastic table cloth. The dollar store sometimes has great figurines that can be painted as well as well priced paints. Remember to cover the children with smocks of some sort if they are painting
- Play pass the parcel to your child’s favourite songs works well and have the prize in the middle of the parcel be something everyone can share (leis for around their necks is an idea or plastic rings).
- Have the children be involved in “making” their food such as decorating an english muffin pizza, putting the fruit on their waffles or decorating the cupcakes themselves.
- If the weather is nice have them playing running games outside as much as possible (relay races, tag etc.) and soliciting the help of a teenager who is involved in camps can be a huge help with games like this.

As for the after-party…I completely agree with Christine – plan some serious relaxation for afterwards, the clean-up can wait