Oxfam made a very nice 3 minute video of a recent Day of Action demanding Starbucks stop trying to muscle possession of Ethiopian regional coffee names. The protesters have beautiful signage and a very clear message. YouTube shows 12,000 views of the video to date.
What appears to be Starbucks corporate response was also posted on YouTube. It's received about 3000 hits.
If you were not sure how to pressure corporations, this looks like a very feasible option.