The two slots you have are primarily there for SLi or Crossfire graphics card. I'm not sure what other expansion cards there are for PCI-E.
Why specifically do you want to save your normal PCI slots?
ummm noob...sli and cf dont run in pci express x1...they run in 2 pci express x16
to answer ur question...some usb/firewire card, some tv turners, etc...
look at newegg