We also threw a halloween party for our son when he was in the 8th grade (2 years ago). We made it open invitation to the entire 8th grade class, distributed fliers, etc.

We hired a DJ and a "fortune Teller" (The girls really liked that more than the boys). We did the basement up, had the dance area down there with the DJ (it is a very large basement separated into two big rooms that connect). I placed orange and purple "Black" lights everywhere, outlining the stairs and the rooms. We had strobe lights and different lights (like a stop sign, etc) for the dance floor.
We had a bon fire going out back and we put hay bales out there for the kids to sit on by the fire. We had food upstairs, constant parent supervision and it only lasted until 11pm (2 1/2 hours- we had to start late because the school had a dance for the 8th graders that night as well, so some of them just came to our house when that was done).
We did a costume contest, and I bought those snap light up bracelets and necklaces for the kids to wear.
Since we do really have a ghost in our house, and we have accounts from people who have lived here since the house was built, I put together a flyer talking about the "Old Man in the Basement" and explained about him and then put down the eyewitness accounts that were written to me by all who had seen him. We passed these out as the kids came over and it really set the tone for the party. Then, about an hour or so into the party, when they were all downstairs dancing, my dh got this old mans mask (REALLY big and the beard goes down to his knees!! LOL) and he walked down the stairs and just stood in the corner. It took a while for anyone to notice, but when they did it was the FUNNIEST thing I have ever seen! The DJ even screamed and freaked out..LOL

That was a super fun night. We didn't get overcrowded..it was just a fun night for all of the kids involved.