Yup. I've got a bunch of Xilinx CPLD boards and if really won't appreciate you doing things like externally driving an output. Be very careful about what you're driving as well as they'll get extremely hot if any reasonable amount of current goes through them.

FPGAs are much more interesting IMO. Bit more expensive but you can do a lot more with them. On the larger ones I've got you can fit a CPU along with a bunch of peripherals cores all into a single chip. Take a look at OpenCores for some free cores to use.