This page should help to get your local bookcrossers known.
In these lists you will find all meetups in the german area which has been reported to me (Wyando). The first list (below) shows you the upcoming meetups for the next 30 days; die second list (in a new window) shows you the meetups which are on a regularly basis (weekly, monthly, etc) which takes place at a fix location (Cafe, bar, resto, etc).
Details for those once in a while meetups are linked with their posts in the german BookCrossing forum. Some cities have meetups at different locations; those are marked with ??? and their details are announced in the german BookCrossing forum a few weeks before they happen.