What is a good HFS+ NAS or network HDD I am wondering what would be a good, if any, NAS i can find with HFS+. My reason for wanting this is that I need the metainformation in the files to stay intact as I am dealing with a lot of OpenMeta tags.

For me this can be any NAS or "external HDD with network connection".

The question has been raised here (Which NAS for Mac users?) previously, but was not answered as to what drives do have HFS+.
So, HFS+ is a closed, proprietary format. For linux to work with this format, it needs hfsprogs, which is a module that supports HFS+.

Most NAS servers use linux-native formats, so if you want HFS+-based filesystems, there are a few ways.

a) Most NAS servers are built with Linux, and most of them have command line. You can load hfsprogs module and write a script to have the system mount your HFS+ formatted drives. In another word, customize the system.

b) Roll your own server, a good Synology enclosure costs about the same price as an Mac mini, you can get an external hard drive and have it running as an server.