I don't have a powerful verbs list, but here's what I did last year with my 6th graders:
- Give examples of verbs that are overused/dull (said, look, etc.).
- Have each student come up with at least 2 of his/her own.
- List all the verbs on the board and together come up with synonyms that would be better. You can incorporate the thesaurus to help you.
- After the list is made, you can print a copy and give it to each student. You can also post it on the wall as a year long reference.
This takes a while, but the students do the work, so it's easier on you
