I really wish there was some universal file system that I could use from all OSes... maybe the one Oracle was working on to replace ext3, ext4, etc.
There are more "universal" network file systems. The premise of most operating systems is that the machine they are on is for that operating system.
Mac OS X does NFS. However, windows doesn't do that out of the box (at least the home/workstation versions). Mac OS X does SAMBA. If you have both partitions running at the same time you can share.
If you have lots of files to share between multiple computers looks into a dedicated file server. However, for very large ones and one OS at a time can see why might want to just pull them straight off the disk.
The overhead for the more modern versions of file systems is that they are journaled and not trivial to implement. ( there is no simple "driver" that is going to get you a correctly functioning journaled FS . If all doing is reading that can blow off the journaling and correctness aspects. ).
By the way, no hope in the Linux ones, including BTRFS (the ZFS-like file system lead by Oracle) is Linux only (like ext3, ext4, etc. ). Besides BTRFS is seriously not ready for prime time. It somewhat works, but not ready for critical data. Probably won't be for a while. (Sun worked on ZFS for years. ). Potentially even more cloudy once the deal closes with Sun and Oracle owns ZFS. How many clones of ZFS do you need when you own the original?