I didn't scroll through all the "ideas" so forgive me if this is a repeat, but..
Give an incentive or IQ points for users to rate the quality of submissions. I've had one submission rated correct in the past year out of 55 submissions. I don't think rating something "correct" should give the same amount of points as the submission itself. Maybe all three quality reviews give the same points amount of points though? The other problem I could see is people just verifying submissions for the points without doing their due diligence.
Or make a badge system for people that review submission qualities?
Users making dozens, even hundred of submissions that just sit there for years is a problem here, for sure. As someone who has reviewed/approved hundreds and hundreds of submissions here, I support Correct submissions being worth more points, because there are a lot of lazy, half-assed, and just plain wrong submissions that come through everyday -- there needs to be incentive for users to strive to meet a certain quality standard.
I love the idea of rewarding people who review other's submissions, but if the incentive was enough to matter, there is the risk that users start reviewing and approving things without really reading/considering just to get the points. So I understand the apprehension to reward approval-labor with points... frustrating as that is.
I think your badge idea is great. :)
How many submissions of other community members have you reviewed? I find the best way to get my own stuff reviewed and rated is to invest time in rating submissions from other people here, especially the work of users who are currently active on the site that week. That said, I still have hundreds of submissions that have never been rated, and maybe never will... but there's definitely an unspoken quid pro quo effect amongst the active approvers.