Custom printed fabrics would obviously be great if you want to design your own garments, but for the beginner DIYer, basic home decor items like curtains and pillows would be super easy and fun to sew.
If you're not a designer, there is a huge collection of designers to browse through. It reminds me a bit of Threadless. Here are a couple of my favorites, which just happen to both have birds.
Multi-Owls by petunias
Doves by troismiettes