Last year we had an army party.  The invitations were ones that I made up with army clip art stating they were being summoned to duty, place, time, etc, stating army attire optional (have extra camo type shirts on hand for those who didn't come in one).  When they arrived, they received army hats, dog tags with their name on it and a folder containing their "list of objectives" to complete. The list of objectives was completing all the games and activities planned. I asked them their name and serial number (numbers the kids came up with) and filled it in. I was dressed as an officer. They also received a camo bag which was simply made. Just buy some camo material and canvas for the straps. Just a simple design with long enough straps to hang cross-wise over their shoulders. I also put one small red, white and blue rhinestones at the top on each side (to satisfy the girls in the group and simple enough that the boys liked them too). In each bag was a pair of camo binoculars.  Activities: Coloring army themed coloring book pages (found on the internet) and each child received a small box of crayons.  Next we went downstairs to the playroom where I had GI joes standing up in makeshift stands and they knocked them down with beanbags I made with the left over camo material.  Then they moved on to pin the hat on the soldier. I drew the picture myself and cut out army hats from some army pamplets I acquired.  Next I had a balloon dart board made with National Guard balloons on a big syrofoam board.  Inside the balloons were activities that they had to complete like - do 2 situps, do 5 jumping jacks - something physical.  Next we had the children kick and punch the stationary karate kick bag that we have a few times. And finally we played "Sergeant says" with my husband leading the crew. For each activity, they received a sticky star on their "list of objectives" marked completed.   Then we went upstairs for cake and presents. The cake was in the shape of a tank.  I used one of his big tanks for the idea and then cut.  That's the one thing I can't describe in details as I winged it, but it wasn't that difficult to figure out.  I used round chocolate mint cookies for the wheels with chocolate squares for the tracks around the wheels, and a long thin chocolate frosting covered lollipop for the big gun.  I put it on a large clear plastic sheet and then crumbled up graham crackers for sand around the tank, silver dipped sugar (cookie) balls for boulders placed here and there, and then used his small plastic army guys placed all over.  The frosting was colored green with black and brown spots (i.e., camo colored).  At the end of the party, I took their bags and gave them a lot of army themed items. Much of it was free. I called our local national guard and asked them if they had anything they could give us for an army themed party.  They were very generous and gave us a box load: camo pencils, army bookmarks, army posters, army pamphlets (from which I cut out the hats for pin the hat on the soldier) and folders (which I used for their objectives), national guard balloons, and they even gave us one national army cap for the birthday boy.    For decorations, using the pamphlets I received I cut out various pictures and pinned them up everywhere. We bought a cheap camo tarp for the tablecloth and put all my son's army stuff (solders, tanks, helicopters, etc.) everywhere.  Although this party seemed very involved, it was not. The kids didn't stop talking about it for weeks after. It was inexpensive and a great success!