I love this idea. We made a commitment to "no theme/low theme" parties this year, and part of that involves using the number (age) or letter (first initial) to personalize standard things like cakes, cupcakes, cookies, etc. This way, the kid feels special and you don't have Buzz Lightyear on everything. I say this as someone who had a giant inflatable Buzz Lightyear at my son's party last year! When he requested Angry Birds for this year, my husband made the low or no theme request. The plan for now is to do the numbers/letters and "generic" colorful birthday decor. If the child insists on a theme, that can be reflected in the dessert, goody bags, invitations, etc. It doesn't have to be on every water bottle and banner, nor does every food offered have to tie in to the "theme."

It's hard, in a way I'm torn. I see some of these super themed parties - and have thrown them myself. It's a fun challenge, making things that match the theme. It's fun to create cute ways to tie in a vegetable tray to the theme of the day... but in the end, the madness has to stop! This number idea (or the correlated letter) can be the "theme" of the party (lots of 5s cropping up all over the place), or it can be incorporated sparingly into other themes. Even the photos used to make the number could be reused every year, with new ones added accordingly.

We recently surprised our son with balloons shaped like a six on the front door of our apartment, which he really liked it a lot. You can see a picture of it here: http://instagram.com/p/R0MEqDEHlg/