Recently, a friend asked me to look for a cheap NAS solution. One of his (many) requirements was native interoperability with MacOS 9. Most NAS solutions integrate well in an environment with modern OS versions, but don't play nice with older SMB or AFP versions.
I looked for weeks, until I found this goodie from Lacie (a french company known for its MAC products):
http://www.lacie.com/products/product.htm?pid=1059 4compatibility:
Windows® 98SE*; Windows® 2000*; Windows® Me*; Windows® XP (SP1 & SP2); Mac® OS 9*/X, Linux 2.4 & higher*
* Only on the Ethernet network
It has everything he wished for, it's cheap and easy to use.
If compatibility isn't an issue, just google around for some reviews. If I remember correctly, most of the reviewers were quite impressed with the solutions from SimpleTech:
http://www.simpletech.com/commercial/simpleshare/i ndex.php