Knit from your stash along.
I found this along and I wholly agree with the concept. I'm just going to tweak my rules.
Rule 1: I will finish everything that is currently waiting in my queue by the end of the year. Because most of my stash is unfinished projects, this will deplete my stash.
Rule 2: When emergency knitting needs to be done, I will buy new yarn and not feel guilty about it. Emergency knitting includes gifts for Christmas/birthdays, and most specifically, Melissa's socks*.
Rule 3: Whenever possible, I will try to get yarn from thrift stores (or old sweaters from thrift stores).
*Melissa, my roommate from last year just got her mission call to the Russia Novosibirsk mission, which is in the middle of Siberia. She's from Las Vegas and has NO winter clothing, so I'm going to make her socks that go to her knees (as she'll be wearing skirts and dresses in Siberia for a year and a half).