How about the toilet paper game. You split them into teams and give them 1/2 (cheap) toilet rolls each and they have to make one member of the team into a "mummy". They also have fun playing with it after - though only good if you don't mind mess!
Just had ds1s 4th bday party at home with 8 of the little lovely's. here's what we did:
2.30 arrive and play outside/inside with a selection of ds1s toys 3ish party games (pass the parcel, musical statues, muscial cushions (same as muscial chairs but safer!), simon says) - we used gold coins as prizes so everyone got something 3.30 ish party tea (picnic style) 4 ish birthday cake 4.15 treasure hunt to find part bags and more gold coins (did this in the garden) 4.30 home time
From experience have found its often best to just let them get on with things, kids generally know how to play together so as long as theres plenty about for them to do it usually works out
If you can't get outside could try doing some crafty stuff indoors, get them all to make a party hat or something
They also love being given a 2' square of bubble wrap each and being instructed to jump on it and make as much noise as possible.
There was a game I read about which involved seeing who could walk down a long stretch of bubble wrap making the least noise, but I concluded there would be too much background pandemonium to be able to judge it.
Pin the tail on the donkey or a variation. Simon says. "Stations" or a variation - each corner of the room has a name (station, football team, etc.) and when the music stops they choose which one to go to. Adult not looking picks one of the 4, and all those chidren are out. Definately sleeping lions if it all gets a bit much!
Shark!! Make 'islands' out of pillow cases or similar and scatter round the room. When the music is playing kids have to pretend they are a dolphin / octopus / seahorse / whale / penguin / etc. You usually have to demonstrate how they have to 'swim' around to the music. When the music stops shout shark! and they all have to get on an island. Keep removing islands till last kid in. If a kid is out; send them to the 'hospital' for a lollipop for being brave while attacked by a shark. This saves kids getting disruptive or whingy whilst the game carries on to the end.
Main tip for kids parties ; go with the flow; have lots of games ideas as you never know which ones will be successful. Keep them short and sweet with quick wins. Kids like just the novelty of playing with several mates at home so will be happy with their own toys for part of the party.
Brace yourself for some brattish behaviour and deal with it swiftly if it occurs!!
Flop in front of rubbish TV or daft film when the kids are in bed later!!
Treasure hunt - chocolate coins blue tacked anywhere you don't mind them going - party bag each to fill. They all get sweets and the one with the most gets a little prize too. Even better if the weather does perk up as you can chuck them out in the garden to do it Good Luck!!!