The one that caught my interest right away is the PCIe module:
http://www.hitechglobal.com/FMCModules/FMC_PCIExpress.htm
There's also a PCIe expansion that works with it, so increase the number of slots to five:
https://www.onestopsystems.com/product/%C2%B5cube3-expansion...
With those, it seems like enough to test out development for storage applications. eg NAS, etc.