  We derive relative proper motions of stars in the fields of globular clusters
M4, M12, M22, NGC 3201, NGC 6362 and NGC 6752 based on a uniform data set
collected between 1997 and 2008. We assign a membership class for each star
with a measured proper motion, and show that these membership classes can be
successfully used to eliminate field stars from color-magnitude diagrams of the
clusters. They also allow for the efficient selection of rare objects such as
blue/yellow/red stragglers and stars from the asymptotic giant branch. Tables
with proper motions and photometry of over 87000 stars are made publicly
available via the Internet.
