1U or 2U servers, preferably i386 or AMD64 for our various services (web, email, revision control, ...). At least 8GB ram and room for two or more disks (we have all our system disks mirrored).
Sometimes large SATA disks
Servers in Asia for mirroring search.cpan.org, perldoc.perl.org and related services (we're well covered in North America and have a server in London, too). Can be virtual or real hardware, but needs to run RHEL (we can provide media and license) and have 4GB ram or more.
Managed Gigabit Switch (~24 ports). We have an old Dell one, but if someone has a spare HP or Cisco quality one...
An industrial strength NAS - NetAPP or EMC or similar.
If you have some other useful spare hardware or can help in another way, email webmaster at perl.org and we'll see if we can make use of it.