Just wondering if anyone has tried using spice to develop any 6502 applications?


Here's one version:
http://sourceforge.net/projects/ngspice/

You can do it, but it is absolutely not recommended unless all other simulation possibilities have proven fruitless. SPICE will take hours to just simulate the CPU's fetch from reset vector in a fully loaded circuit environment.

SPICE is tailored more for integrated circuit simulation, where it's just not possible to tweak an IC afterwards.

It's much better if you acquire a Verilog or VHDL model of the processor instead, and use that to perform a behavioral simulation instead. If additional detail is required, these environments also allow for gate-level simulation too (once you rewrite the code to represent individual gates instead of a generic behavioral model). It's VERY rare to have to go beyond gate-level simulation, though.