If you're doing HardCopy-style structured ASICs, in theory you could put a fastish 32-bit processor and Ethernet MAC on the ASIC itself. It'd probably only take up a smallish proportion of the chip and you'd just need boot flash and Ethernet PHY chips externally. Not sure how much sense this would make though.
Depending on expense, i'd look at adding a small XMOS processor to the board. It being transputer in essence was designed to talk other chips like ASICs and other XMOS. The ASIC is left doing its special magic, the XMOS handles everything else (including block submits etc.) and can be easily connected up into massive rigs as required.
I don't like this idea too much. I'd keep the ASIC/FPGA interface as simple as possible, but I'd prefer a bus for easy scalability. I²C springs to my mind.
This way you can keep the ASIC simple and don't waste precious space, don't waste the control processor circuitry when chaining multiple ASICs, and can use the same ASIC for both PCIe-based accelerator cards and standalone mining boards. The latter would get a simple ARM SoC with updatable firmware (based on linux?) and an ethernet interface.
Edit 2: Also, a totally untested 90MHz/90 MHash/sec bitstream for the DE2-115 is now in a branch on my git repo. PowerPlay estimates 4.4W of heat, I think? Anyway, don't blame me if you blow up your expensive board. There's a reason I'm not including instructions here.
I'm fairly certain that this estimate is way too low.