Planning a party

Well, my husband's boss has been lenient and he gets off half-an-hour early on Friday so that he can transport children here and help with the party. So now I need to plan...we've decided on a Lego party with a simple cake. Nothing like this. Some games ideas that I found while surfing this afternoon:

1. 2 minutes to build the tallest tower that doesn't fall over (using a set number of blocks)
2. Lego drop - dropping Lego into a bottle or bowl from a height (top of our stairs???)
3. Naughts and Crosses tournament, using Lego
4. How many Lego in a Jar - guessing game
5. Put the hat on the Lego man (or man into the Lego scene)

Anyone got any other ideas, preferably that are free and can be conducted in a small house (it is potentially raining on Friday). Because our son now only has 1 1/2 days left at school, I'm going to get him to do some organising for his own party - keep him busy and keep Mr Boredom away. Now we just have to hope that he remembers to give out all three invitations tomorrow.