Ours doesn't really leave gifts but he does get up to "elf hijinks" every night! He returns from the North Pole and then gets bored while everyone is sleeping. Here's what he did last year.
- drew a Christmas tree on our sliding glass door (required me to buy window markers, you could also use dry erase if you have them already!)
- was found dangling from a ceiling fan
- played with the kids' toys (I took pics of him playing with the toys- him inside the ball popper, him riding a train, etc and then printed them out on computer paper)
- went potty (green food coloring + marshmallow "poop")
- made hot chocolate
- played cards with friends
- got sent to time out
- enjoyed a bath in marshmallows
- made spaghetti like Buddy does in Elf- spaghetti with syrup
- was found enjoying the cold in the fridge
- built a Christmas tree out of cans
- decorated the Christmas tree in DD's underwear
- went fishing in hot chocolate (toothpick + string)
- was found outside in the cold
- was found in daddy's car, shopping bag of Christmas bows next to him
- had story time with his friends
- introduced the kids to "Elf Yourself", a free site
- made snow angels in flour
- built snowmen out of marshmallows
- brought the kids Christmas coloring books (from the dollar bins)
- cuddled up with a bowl of popcorn and his friends to watch "Elf"
- TP'ed the tree
- wrapped the bathroom door closed
- started a band with his friends
- drew a Christmas tree on the bathroom mirror with toothpaste
- decorated the house with candy canes alllll over
Whew. Hope that helps. The only things I bought specifically for the elf were the window markers (and again, you could improvise and use what you have, even lipstick) and the dollar coloring books. We used the candy canes in their stockings, so even those weren't bought just for him. I cannot wait to start again this year!