Here's a big collection of Acceptance and Commitment Therapy worksheets from Russ Harris, author of several ACT books. For some of these worksheets, reading the book(s) is going to be a help. But many are self-explanatory. Check out the Free Stuff tab on Harris's site for additional ACT-based help--videos, audio, etc.
Psychotherapy worksheets of all kinds--depression, anxiety, anger management, stress reduction, self-esteem, groups, individuals, couples, adults, teens, children, CBT, DBT, ACT, PTSD, OCD, BPD...and more.