This post is very old. Please bear in mind that information here might be incorrect or obsolete, and links can be broken. If something seems wrong, please feel free to comment or contact me and I'll update the post.
Finally found one – Roundup. Supports several DB backends (SQLite, PostgreSQL) and just works. I’ve upgraded my local PostgreSQL to the 8.0 final and managed to get Roundup running in less than one hour. It works, looks good and is probably enough for my purposes.
Related posts: