Best choice for a Linux temporary files server?

Solution 1:

If you can use a FreeBSD solution rather than Linux, FreeNAS is a great NAS option that's easy to install and configure and has a huge range of options for connectivity and access control. There's also a Linux version of the project underway, but I'm not certain how feature-complete it is.

There's also OpenFiler on the Linux side, but we've found FreeNAS better for our varied needs (which admittedly sound quite a bit different than yours).

Edit: Sounds like you need something to run on an existing Linux server rather than its own hardware. If this is a necessity I'd think about running one of these options as a VM under KVM or Xen.