I'm quite new to this craft business, but there are some fantastic blogs out there with some great ideas on them, some of which are on my blog roll to the right of this page.
The inspiration for this birthday t-shirt for my nephew Archie, came from the House On Hill Road blog.
The author of the blog makes one every year for her kids. A birthday t-shirt can be anything you want it to be, although I guess it should probably have the age of the child on it somewhere in words, numbers or whatever you fancy!
For this one, I printed the different size numbers, traced them onto Heat & Bond and then sewed them on with blanket stitch. This is the first one I've done, next time I think I'll experiment with images and writing too.
UPDATE 19/5/10 : For more sewing projects please visit my new blog Little Island In The Med