Whenever I need some inspiration for a party or social event, I like to take a quick trip to my local party store. Although there are many tacky and cliche items at these stores (I'm getting a visual image of the inflatable palm trees and the "over the hill" walking cane with attached bicycle horn), if you can get past these, you should be able to draw ideas from the rest of the store.
Take a look at the thematic aisles --- you can find ideas for tropical beach parties, sports-related parties, Mardi Gras themes, summer picnics, and many others.
Take a stroll down the tablecloth aisle. You can find vinyl skirting and tablecoverings. You can also find large rolls of thin plastic sheeting, in a variety of colors. Think outside of the box in this aisle -- you can use the colored sheeting for wall coverings to enhance your theme. A Teenage Mutant Ninja Turtle or Sewer Themed kids party can be created in an unfinished basement, when the walls are covered in gray sheeting that's been painted with red "bricks" made from kitchen sponge imprints. Plastic sheeting can be your temporary canvas -- almost like a stage backdrop --- that will transform your everyday space into whatever exotic locale you can imagine.
A quick trip to the plasticware aisle can give you ideas on colors for your service to fit your party's theme. Or perhaps you're having an Olympic themed party, and you're looking for the perfect way to mass produce the Olympic rings. Just buy stacks of red, green, blue, yellow and black plastic/paper plates, remove the interior circle of plastic/paper, staple the various exteriors together, and you've got your rings!
The bottom line is to have fun with your trip, think outside of the box, and take notes! The sky's the limit in terms of your creativity, and your party's budget will be saved if you can rely on your imagination.