Here's another interesting one. Convert into party list preferential voting:
Step one: You have two options, either increase the number of seats per riding thereby making the parliament in question much larger, or consolidate neighboring ridings into bigger ones, keeping the same number of seats. Either way you should have a total of six members per constituency.
Step two: Compile a list of results for every riding, give the party in first place three seats, the party in second place two, and the party in third place one.
Step three: Compile results, and determine government.
Naturally this system would only work in a country with three or more political parties. For a country with only two, like the US, have the first place party have two seats and the second place have one.