I don't know exactly what you want to do, so it's hard to say anything specific, but there are some really good DIY twitter accounts and there's some good stuff on pinterest, too. Good luck :)
I have always been a fan of DIY items. Especially decorations. I suggest paper lanterns and stringing them up around your room. Or even paper snowflakes & butterflies taped to your walls for the simple yet beautiful kind. If you want to go more complicated, try to find old metal bracelets and crystals to make mini chandeliers and stringing them up.
Even add some of our painting on the wall. I would suggest websites, but hey! It's DIY!
I love DIY home decor products. Although now a days I do not get enough time to do DIY projects with my two young kids. Still I can share some of my works with you. Please have a look at my blog : tidyhomeblog.blogspot.ca/search/label/DIY%20Project
That is an awfully vague question. We don't know your personal taste so it would be hard to suggest anything. Why not go on Pintrest and get some ideas from there?