One thing that everyone comments on in our nursery is our wall sticker! Most people think that I've painted a tree on the wall but I have to tell them nope, it's just a really big sticker. But it looks great on our dark wall and gives a bit of a break from more framed art, canvases etc.
The best part I think is that most of them are removable, which means if you're renting you can still use these! And they are becoming so popular I have seen stands in the middle of shopping centres, and limited bits and pieces at big department stores like K-Mart and Myer. So you can do it onan absolute budget.
But of course, my favourite place to find wall stickers is Etsy.com - I ordered mine from Israel! There is SO much choice so you do need a bit of an idea of what you're looking for to start searching (I searched for Bird Sticker Wall Decal and had about 2000 results!). The prices vary dramatically depending on size but best of all for most stickers you can specify the colours and even which way around you want the sticker to go, so you really can get exactly what you want.
Anyway enjoy these little bits of inspiration!