hi there, complete newbie (err, long-time lurker...), sorry for lacking manners and not introducing myself...
of course there were german pirates, try looking for "godeke michels" and "klaus störtebeker", they were the most famous ones, i think. also worth a try might be "viktualienbrüder" or "vitalienbrüder", that's the name of störtebeker's and michels' men. btw, their big time was end of 13hundreds, early 14hundreds, and there's a statue of störtebeker in hamburg (where he was beheaded). he's rather famous here for the trick he's said to have done to rescue his men: they had to stand in line when their captain was decapitated, and after loosing his head, he is said to have stood up and run along this line, and every man he passed went free. he did a long run, right until a soldier tripped him...
dunno about your german skills, but you might also try searching for "seeräuber" (um, just realised that the other words probably all come up with german sites...)
don't have any actual links cause i always thought the caribbean a tad more interesting than those cold grey waters so close to my doorstep but i'm sure you'll find a lot. the "bremen überseemuseum" did a nice exhibition on pirates some years ago, and as far as i remember, they also had a nice website about it. maybe you're lucky and it's still running (and might have interesting links!).
not german but also operating around our coasts (i.e. north and east seas) were the vikings, even longer ago than störtebeker and his bunch but my favorites besides the caribbean pirates
hope i was at least a little bit helpful
