Let me start the ball rolling:
1. Galaxies wind themselves up too fast
2. Comets disintegrate too quickly
3. Not enough mud on the sea floor
4. Not enough sodium in the sea
5. The Earths magnetic field is decaying too fast
6. Many strata are too tightly bent
7. Injected sandstone shortens geologic ages
8. Fossil radioactivity shortens geologic ages to a few years
9. Helium in the wrong places
10. Not enough stone age skeletons
11. Agriculture is too recent
12. History is too short
http://www.answersingenesis.org/docs/4005.asp
It is fun to read and try to spot the way facts are distorted to fit the arguement.