Wow, lots of great ideas, thank you!!
I have spent the past hour looking for an unique
Lego invitation design we can make up. Found some good ones that I just need to figure out how to duplicate.
Not sure how many legos you have but what about a Lego build comedy for a game? Each child can have a number of legos and they have to build the tallest or longest structure in a certain amount of time without it falling over.
You may want to check the lego store online to see wha sale items (like the Lego figure keychains) they have on sale. Would be a cute gift bag item.
Also, the Lego store sells a mini figure ice tray. It onl makes 8 ice minifigs at a time but the freeze in about an hour and if you start a few days ahead you oul have a number of them for drinks.
I wondered how this other mom made these! One of the links Mom2Ben provided showed a plateful of gummy legos. Thanks for the tip! I'm really wishing I was "with it" 3 or 4 days ago. I saw the wheel assortment set on sale at Lego but was not in "birthday planning" mode at the time and missed it.
You are in luck - I have lots of links

My son - not so much. He wanted a Lego Party, but I ended up in the hospital with quadruple pneumonia and had to scale back the party.
I'm loving the links, thank you. Quadruple pneumonia?

I hope you are much better now!
My friend's son had a Lego party for his 7th, and she was smarter than I was -- she made a half sheet cake and used those candy bricks to spell out his name on it.
Favor boxes are easy too -- you mentioned the brick candy, and then there are Lego fruit snacks you can put in there too. Lego.com is having a half off sale at the moment, and you can get their favor pack (
http://shop.lego.com/Product/?p=66373) with 8 mini sets for $10 right now. We also ordered a roll of stickers from Smilemakers (
www.smilemakers.com/shop-by-product/stickers/character-stickers/LEGO.html and they have Racer ones too) and put a few of those in each bag.
Ohh I like that idea with the candy bricks spelling out his name on the cake. Much simplier than trying to make make brick/block cakes. Thanks!
My husband found the Lego favour packs on sale at ToysrUs for $20 (I think) when they were listed at $30 (purchased 2). But $10?? Jeez... I'm tempted to dig through my receipts. If Lego is still offering the free shipping and I have the receipts, I may get them from Lego and return the ToysrUs ones..
And thanks for letting me know about the stickers!
(update - turns out the Lego favour packs were $25 here and we paid $18. Which is still a good price considering there is 4 creator airplanes & 4 creator 4x4 jeeps in the pack = $2.25 each!)
Also while I was in the Lego store purchasing a gift another mom was ahead of me buying the Lego man ice cube trays - she was going to melt crayons and pour the wax into the tray to make Lego shaped crayons! I thought that was a brilliant idea but way too much work for me with my shoulder at the time.
LOL - I like the idea of melting crayons for lego-shaped crayons. We have tons of broken bits & pieces odds & ends of crayons around here! Hmm... I never tried this before but I might if I get the lego man ice cube trays.
If you can find them, the little packs of the Series 3 minifigs can be got for as low as $1.99 in some stores (don't bother with Toys R Us, they have them up to 3.99 or something obscene.)
Yes, I was wondering if I could still find these. Only, we were paying $3 a piece here at Wal-Mart. If I come across them cheaper I'll grab them!
The first thing that came to mind was the Building stations at the Downtown Disney Lego store and how long kids can just sit and build. My DD has never owned a Lego but even she and her girl cousins sat for a good while. What about setting up an area for that? It might take too many legos unless you already own a lot.
This is a great idea and something I'm trying to figure out how to set up. Currently we keep all lego in the living room. I *know* if I let the kids keep them in their rooms (or playroom), many pieces will go missing. However, I do not want lots of kids all playing at once with lego in the living room.
I think I'll have to temporarily move a lot of lego into the playroom for the day and make sure it gets cleaned up immediately that night. And I may need to hit our local Craigslist & Kijijii to pick up some loose lego cheap. After we re-assemble our existing jumbled up sets for decoration - I wonder just how many pieces we will have left for playing with.