We have developed hardware and software for fluorescence photon counting applications such as FCS and FRET with single or multi-line excitation.
You can read about the FPGA-based hardware on Arxiv or in the American Journal of Physics sometime later this year.
An overview of the device and associated software can be found on our wiki, which is also linked at the right.
If you just want to build the hardware, you can start with the manual.
If you just want to use the analysis software, you can start with the installation and use instructions on Github. The software is primarily written in Python and run under Ubuntu Linux, however it should run on other platforms. At least one of us uses it on Mac OS X.
Ben Gamari did most of the hardware and software design.