Nothing at least right now. Better to carefully analyze the whole incident, determine what things went wrong, and then do something no one ever does--figure out if this was an extremely rare event not likely to happen ever again, or something that was the harbinger of a TREND. Like 19 guys commandeering three jets and. . well, you know.
As individuals, and as a society, we're not built to look at events from a statistical perspective. Nineteen Arabs pull off a once-in-a-lifetime stunt and everyone reacts as though it could happen everyday. The response: we encourage millions of our tax dollars to be spent on "airline safety". And thats not all: we cheerfully allow our phones to be tapped, our mail read, and our rights trashed. Oh, and let us not forget about Iraq--didn't we go there to make sure some angry Egyptians and Saudis wouldn't fly into our skyscrapers again? When you see (as you doubtless will in a few months) mortar rounds falling in the Green Zone, credit not only Messrs Wolfowitz, Perle, Cheney, Feith, Bush, Atta, and Brit Hume---but ourselves. We should have FORESEEN and PREVENTED that kind of behavior!
Still, even the Republican Right is beginning to ask whether all of the restrictions, excess, fear, etc. were really worth the trouble. One could almost see the light of sweet reason at the end of the tunnel.
But then. . .
Comes now Mr. Cho, the college/Korean/seriously troubled nut job with enough asterisks behind his name to populate THREE Wikipedias. Born in Korea, raised in the U.S., history of mental illness, missed by the counselors, slipped through Virginia's molecule-thin gun control safety net--managed to take out 33 good kids in a hail of bullets.
Immediate thought: Well, if we can't reverse time and lock the kid up before it happened, how in the hell do we make sure it doesn't happen again? Immediate answer: Prohibit Koreans named Cho from attending college, banning firearms everywhere, tightening the notoriously-lax Virginia gun controls AND (okay, paradoxically) allowing everyone to carry guns... (Let's pause for a moment--Readers: have you ever been to a college kegger? Consider a kegger where everyone is armed. Not pretty, is it?)
Anyhow, the local television stations are having a field day with this event, given that everyone wants to make sure it doesn't happen again. Ever. No one is asking whether it's a statistical fluke, the case of a seriously-bent individual reacting to perceived slights in the worst way possible.
Instead, Mr. Cho's terrible behavior will probably result in college lockdowns, fences, frisks, curfews and the eventual banning everything from scissors to very sharp pencils. Tuition will double as colleges have to pay for burly Iraq-hardened security guards patrolling the halls. Spring mayhem (i.e. harmless-but-loud mob scenes, parties after hours, people acting stupid) will be a thing of the past. Another Cho might be there, drinking beer and planning awful things.
So, everyone should probably say sayanara to acting really stupid after finals, being obnoxious, IM'ing the Gurl of Your Dreams, or blurting out offensive and crazy language.
After all, Cho did most of that kind of thing before he killed a lot of people.
Now, thanks to him, you won't be able to do any of that at all. Even if you just wanted to get friendly with the brunette with the Blackberry in English class.
Better we should take the Cho thing for what it is: an abberation. A very weird event. Certainly we should explore ways to make it more difficult for dangerous people to enter college, but that would involve identifying the danger beforehand. Think: how many brilliant but socially-inept people that you know could pass that test?
Could you?
So, my sure-to-be-ignored advice for the authorities, lawmakers, and especially the media types is simply this: chill. Cool off. Treat thi as an isolated event. Ignore the pundits' call for greater strictures. Keep the National Guard off campus--they're needed, um, elsewhere.
Listen: Mr. Cho was a rarity. A nutjob, to be sure, but a rarity nonetheless. We likely won't see someone like him again because college kids will be inclined to notify the authorities of any behavior that fits the Cho paradigm. As in junior high, collge students have always been able to identify the truly dangerous amongst the population and avoid same.
Get a grip. Learn from statistics: That is. . .just because it happened once doesn't mean it's a fracking trend.
UPDATE:
After reading the comments, and listening to the media frenzy over this thing, I'd like to reiterate my position that whatever measure is immediately chosen to "solve" the problem will likely be the worst one possible. Given that VA is not likely to change it's gun laws (too much revenue from New Yorkers wanting to pack heat) the only thing that will likely change will be greater "security measures"--up to and including a camera in each dorm room. I think a better way would be to wait until all the evidence is in, then examine how the system parts can be tweaked to deter this kind of thing from happening again.
For example: For the gun purchases, institute a waiting period that will actually allow time for a real background check. The smallest software company probably knows more about their customers than gun shop owners do. For the system, consider a requirement that allows the purchaser to sign an authorization allowing the gun shop owner to check all appropriate mental facility records. This will run afoul of all kinds of privacy acts, but it might be workable.
As for on-campus weirdness, I still think the the open court paradigm is a good one. If someone is a stalker--as Cho apparently was--let the person he stalked file a charge on him with the campus administration. If the charge is serious, then a panel should be convened that will allow the defendant (the stalker, for example) to present his case. If he doesn't do so well, then the panel can decide the next step.