Doug & Paige's Fun Carnival Wedding as found on Greenweddingshoes http://greenweddingshoes.blogspot.com/2009/06/real-wedding-doug-paiges-fun-carnival.html
& Courtney and Charlies Carnival Wedding as found on The Knot http://weddings.theknot.com/Real-Weddings/46317/view.aspx?id=46317&type=1&knot_pick=true&ps=8&keep=946514776
We have our "big top" we plan on having the ceremony inside the tent then our reception will be outdoors, we will have a few carnival games set up, and are looking into getting a bouncy castle for the wee ones and a small ferris wheel to complete the "carnival" at some point we'll throw in the first dance and cake cutting, and need to figure out when would be best to serve food and if we want to bother with dancing. I think with or without it will still be a blast. We are so excited planning this, it makes us confident that things happen for a reason, our original planning was a little lacklustre but now we both have a similar vision and are stoked to see it come to life!
Have you seen the yellow circus wedding? It was all over the blogosphere a couple months ago I think. You might find some great inspiration with that too, like their kissing booth for example.