Swissair bought a preferential bidding system from a canadian company called Adopt in the late 90's, with mixed success.
Implementing the complex rule system, a mix of JAA, various collective contracts and a relatively complicated set of possible bids was not only expensive, but cost us a lot of time and credit with the employees.
Still, a notable improvement in general roster satisfaction was noticed after a few months of "tuning" and relentless instruction and marketing efforts.
In the end, the ever-growing demands set upon the software to not only satisfy bids, but also introduce a "fair-share" element for free days and block hours, considerably diminished the system's capability to function.
As far as I know, Swiss now operate with software tools from Jeppesen, and a somewhat simplified set of possible bidding.
Final note: as a single first officer and bidding system instructor, I absolutely loved what the bidding system did for me: better sectors on short and long haul, and the occasional stroke of luck with multiple "leftover" off days being attributed in a lump. The feedback from the guys with big families, part time contracts, other constraints or simply a bad case of "schedule envy" were far less positive at the time.
Really final note: I'm not aware of an off-the-shelf software solution being available for bidding system, and I can't imagine such a system being affordable for a small or medium-sized outfit....