Roman horse boots excavated at Kalefeld [source - there is also a nice decorative elements from a knife case]. See also this gallery from the press conference for an axe, other finds including a coin, etc.
Kalefeld is 100km S of Hanover, it does not seem to have any ancient structures that would indicate a town with which to link the battle which, as Adrian points out, is unusual. It's also beyond the Rhine, which initially led some to think that the battle was Germans vs. Germans, but the finds have confirmed that it was Romans vs. Germans fighting sometime between AD 200 and 250. [map]
As Adrian points out, people always like to link these sorts of things to someone famous, so the current favorite is Maximinus Thrax.
Discovery of Roman Battlefield Poses Historical Riddle - Spiegel
[Source - see also for photos of topography]