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
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.