I first want to thanks all the people who submit ideas.  I love this website and use it every year for my kids parties. This year my 7 year old son wanted a lego birthday party theme.  Here's what we did for the party: My son Spencer actually came up with the design of the invitation.  It was the side view of a lego brick.  It was a folded piece of colored card stock paper which measured 3 1/2 X 5 1/2.  I used a square punch to cut out squares along the top. You can use scissors if you don't have a square punch.  There were 4 alternating squares cutouts along the fold. The inside read: Calling all Lego Fans! It's Spencer's 7th Birthday! Blast on over to "Legoland" with your creativity for Endless Building Fun!   Let's Party on (date)- Cake, Games and Lots of Lego Building Fun from (times) - At Legoland (our address) - RSVP to the Brick Master (phone number). We hand delivered them so we put in a few lego bricks in each envelope to get them excited about the party.  As the children arrived I had them sort a big pile of legos (bought a big bucket for the party) by color. That kept them busy until all had arrived. We had a Lego Building Contest. I had my son take a picture with each guest and their lego creation.  I then made up award titles, one for each child (example: tallest tower, most colorful, most creative, coolest, etc.) and had an awards ceremony and handed out play medals to each child.  They played a Tallest Tower Lego Relay Race. Another game was Guess How Many Lego's in a Jar, winner got to take the lego's home. Then we played Pin the Dots on the Lego Brick.  The kids thought the table decorations were lots of fun. We used a green table cloth, red plates, blue napkins, yellow cups and colored bendy straws. The centerpieces for the table were lego creations that my son built prior to the party.  I sprinkled Lego Brick Candy (bought in bulk at a candy store in the mall) all over the table like confetti.  Colored ballons on all the chairs, but the best part was the place mats and name cards. I had only one piece of this great lego scrapbook paper. You can find it online if you search for Sugar Tree scrapbook paper, then look for Steve's pages on that sight.  The paper had a lego airplane on it with floating lego bricks. Since I only had one sheet, I made color copies of it and cut out the airplane and bricks.  I then found lego facts online and printed them out on white paper and cut them out in the shape of clouds. I glued the airplane, lego fact clouds, and floating lego bricks on a piece of light blue paper, and then laminated them to make the placemats.  I've found that children are always fighting over who will sit next to the birthday boy so I made name cards for each child.  I printed their names on white paper and made the name card holders out of lego bricks.  I put the name cards and placemats at each place setting on the table.  I just made a lego brick cake out of a rectangle cake and 4 cupcakes. I then wrote the word "lego" in the same blue frosting of the cake on each of the cupcakes.  I had fun making the goodie bags which looked like lego bricks.  I found brightly colored paper bags at the party store.  Each colored bag had 6 circles in the same color with the word "Lego" printed on them.  Make sure you buy extra bags to print out the lego cirles. I then used pot dots (scrapbook supply store) to attach the 6 circles on each bag.  I filled the bags with 2 inexpensive lego sets ($2.50 at Five Below and $.75 at Walmart), a lego pencil (lego store), and a ziplock bag filled with the lego brick candy (candy store in mall).  Each child also got to take home their medal and lego creation they built, and their placemat.  The thank you notes were the same design as the invitations, and I put in a copy of the pictures of my son with their friend.  I've given lots of parties for my son, and the children enjoyed this one the best. The children just loved the lego building and all were extremely well behaved which is alway a bonus! Good Luck!