Remember this post from, oh, nearly a year ago?
I actually finished folding the T-Rex in May. For months afterwards, it was nothing but a pile of paper bones in a shoebox, since I was too busy (and equally lazy) to go about assembling it. Finally, on the perpetual quest to get things done, today I found the motivation to give it a try. With the big help of my dad and brother, I was able to replicate the display configuration the book suggests, and the creature now fills an empty shelf pretty nicely.
This T-Rex was designed by Issei Yoshino, and it's modular, using 21 pieces of paper (approximately 6" squares). It's not altogether anatomically accurate, but for origami it's pretty good! I started this project last winter quarter, as way to relax and de-stress while studying and doing homework. (It worked wonders helping me stay calm - I wish I had started the habit as a freshman.) It was also very fun and highly educational. I felt it took my origami abilities to a new level, because the sequences of folds are so ingenious and unusual. At the same time, it's not so "impossibly" hard as some other intricate models out there.
Definitely worth a try if you're looking for a larger project. It's one of those rare ones where you are sorry to come to the end. As an aside, I can also recommend using old notebook paper, if you have any lying around. It was the right thickness and very forgiving, plus it gives the skeleton a slightly antique look. ;)