ZODB is awesome and overlooked, IMHO. I'm biased I guess because I was involved in making Durus which is inspired by ZODB. The ZODB model is not appropriate for all applications (optimistic concurrency control) but for the applications it works for, it's great. Very easy to develop with (no relational-to-OO mismatch) and performance can be great if you design your model carefully. The client caching of data is great. It is a bit like memcache but the data is already there as objects in RAM. The database server will invalidate the cache for you, no manual invalidation needed.
I developed a web application in 2004 using Quixote and Durus. I wonder how many developers outside of MEMS Exchange ever used both of those packages. Somehow I had not yet encountered a proper ORM (I didn't discover SQLObject until later, and Django wasn't out yet), so I liked Durus at the time. That web application is still running, and in the years since then, I've had to handle several escalated customer support cases, and I often wished I had chosen a relational database so I could easily do ad-hoc queries. So Durus probably wasn't the best choice for my application, but that's not your fault. And one thing I liked about Durus was that the implementation was simple enough that I felt I could really understand how it worked. So thanks for that.
