Hi,
Great to see people visiting Oldenburg.
A good place I know is Zucalo.
Donnerschweer Str. 31
26123 Oldenburg, Germany
+49 441 9849868
But if you want to hang around in the pedestrial city center (in fact, the largest pedestrian area in the whole of Germany) - then you can stop by at a cafe cleverly called Bar Celona, Markt 4 26122 Oldenburg Telefon: 0441 / 248 95 25.
There is also a 400th Kramer Markt in Oldenburg this weekend, (some websites say that Oldenburg goes head over heels during these week, but I would call it a slight exaggeration). However still:
http://www.kramermarkt.info/ I am around on Sunday, give me a shout if you feel like meeting up for a coffee.
Tornadogirl