How about a licensing requirement for non-earning, non implementing companies? If they don't have revenues that haven't been awarded by a judge, require them to license according to a schedule determined by a regulatory board.

Hm, good point. My difficulty was this: if a company holds patents that it is not exploiting, all they're doing is adding unneeded pressure on competitors who have to think twice about implementing something similar because you never know when the other guys might sue. On the other hand, it also seems unfair to force patents away from companies that, while having financial difficulties, would also actually like to exploit those patents and simply need some time to find additional income sources.

This would actually be a good idea: such companies should be required to either present a good schedule for how they intend to actively use the patents they hold, with the implementation of that schedule supervised by a third-party (maybe state?) representative. Companies that fail to implement their patents should be subject to limitations that discourage them from using the patents in an anti-competitive fashion, or simply for financial gains that do not result in any implementation.

There could be a ton of variations on this theme. For instance, companies could be required to pay a certain fee for each patent they hold, that decreases if the patent is actually implemented and increases (possibly to impractical amounts) for every year that it is not implemented. This way, companies would be discouraged from hoarding patents, while actively offering an incentive for implementing technology they claim to be patentable.