The last GE was my first and it was a wonderful experience! I strongly urge all members to take part in it. Don't stress about what to buy, you will get a list of likes and dislikes for your buddy. And really, can you ever have too much stuff for your furbaby?!
Looking over the thank you threads from the last GE will give you a good idea of the presents other people have gotten. Most send lots of toys, blankets, bows, clothes, treats, and some send a little something for the furbaby's momma!
I don't have all the answers since I've only participated in one GE, but feel free to PM me if you need some advice or need some detective work done!