Try this site  http://www.zippozap.com/ Hope this might help you.

Namejet is the one I'm most familiar with, but I just realized that Snapnames has .de as one of the options under their Advanced Search. However, I can't ever seem to get a list of all the .de expiring names to come up. If I enter in certain words (or parts of a word) it will come up with 1 exact match that I can backorder, but that's it.

I did take a look at Pool. I've never been able to find .de names on GoDaddy, despite the fact that I know there are some registered there. Maybe expiring .de names automatically get taken over by DENIC or something.

I also found a couple of German places that seem to list expiring names, but you have to pay for a subscription. Freshdrop is another option - I check there periodically.

Is Namejet the only place you've checked? There are so many auction options anymore, that it's good to periodically check them all as you never know what you might find.  Granted, there are also so many options that can be a time consuming task as well.

Hey Nadia! There seem to be quite a lot of .DE domains at Pool.com