ATA (IDE), ZorroII, SCSI all wants a large number of I/O pins. There a currently 4 remaining. A few more possible by reusing boot configuration pins. Getting larger fpga means BGA and that is a path you don't want to go.
But fpgas are capable of really fast communications, esp the standard spartan3. So a possibility is to use the leftover I/O to connect another fpga to hookup these things. Essentially a "south bridge" running on a pseudo serial bus.
Not minding the cost of an extra fpga, special copper trace requirements, support circuitry, power, and connectors.