OpenADC is an open-source ADC module that fits many FPGAs, and you can use this code for basically any ADC or other streaming data interface. Here is the ZTEX USB 1.11 connected to the OpenADC module:
This reference design includes a Python-based application on the computer which handles downloading & displaying data:
See http://www.assembla.com/spaces/openadc for the wiki, code-base, etc. Specific details of using the ZTEX board are on the https://www.assembla.com/spaces/openadc/wiki/ZTEX_USB-FPGA_Module page.