Here's an Olympics watch list:
100--Gemilli is the only real threat here, and I think he's a legitimate threat to make the finals, although medalling is out of the question. Would love to see PRs, at least, from Ronalds Arajs, Marek Niit (although this strikes me as the wrong event for him), R. Sakalauskas, Angel David Rodriguez, and D. Kuc. Of the latter bunch, Sakalauskas, if healthy, has the most potential. He was injured at the Euros, so we'll have to wait and see.
200--I don't think I need to tell anyone here who Christophe LeMaitre is. I've been arguing he's a 200m man for two years now, and I'm predicting silver for him. Yes, silver. There are only two people who can prevent that: Blake and Bolt, and surely at least one of them will get caught for doping before the final.
Niit stands out among the rest. Oddly, his 100 and 400 times are better than his 200, but I'm hoping that's a result of collegiate schedules. Based on the 100-400 PRs, I see no reason he can't go sub 20, although he currently isn't close, and he did finish the NCAA season on a weak note that was never explained. If he's in good form, he could advance several rounds. Hession is in, but he's awful nowadays. Pavel Maslek, the young 400 specialist, is listed. I don't know what to expect from him. There's a guy from Kazakstan, one from the Ukraine, one from Poland, etc, but their current PR's suggest they'll exit quickly.
400--this is where it gets interesting. Karma seems to have caught up with mega-drug-cheat LaShawn Merritt. He's nursing a mild hamstring pull. If he pulls it again and can't finish a race, this event is wide open and we have a lot of possibilities, even without the aging Wariner:
the Borlees--Kevin B. recently beat Kirani James and won a massive Diamond League race. If Merrit is out, he's as much a favorite as anyone in the world.
Jonathan B--lately Kevin has an edge but it never hurts to double your chances!
Martyn Rooney--has had a real renaissance this year, running multiple sub 45's. He's also got the home crowd. Could very well be a finalist.
Pavel Maslak--very young and very good. If he's peaking he could go sub 45 for the first time. His PR is 45.17, so he's a potential finalist. Keep your fingers crossed.
Marcell Diak Nagy--also very young, but perhaps not as developed as Maslak. Still, watch out for the young Hungarian.
Steven Solomon--a personal favorite. The Aussie is the second youngest runner in the field, running ridiculous times for his age (PR of 45.54 and he just turned 19!!!). Expect that PR to fall.
800--This event would be as wide open as the 400 if only something were to happen to Rudisha (cross your fingers and wish good luck to the drug testers). As long as Rudisha runs, however, he wins. Bet your house on it. In the meanwhile, we've got a lot of great runners in the fight for the silver:
Kszczot--brilliant young Pole. Gutsy. Not afraid to take it out. Hopefully, he didn't peak too early (which happened to him during the indoor season). At his best, he can outrun anyone.
Lewandowski--the other Pole. I put him a notch below K, but not by much. He's a seasoned championship performer in his prime, and definitely in the medal hunt.
Nick Symmonds--Has a blistering kick and some excellent PR's but he needs for the race to fall into place just right. I'll be shocked if he doesn't make the finals.
Jeff Risely--may choose to run only the 1500. Solid PR's in the 1:44's, but that probably won't cut it this year. Still, the Aussie can make noise when he's at his best.
Reina--I feel like the Spaniard is getting a bit old, but he has gone into the 1:44's this year.
Borzokovsky--the wild card. His PR's this year are lousy, so he may be too far past his prime, like Wariner. But you simply count this guy out, given his past record (which includes Olympic gold).
1500--Another fun event. Honestly, I think anything can happen.
Nick Willis (NZL)--may actually be peaking at the right time. He pushed himself incredibly hard and lost a gutty Diamond League race recently. I suspect that was a test of fitness. He silvered last time, and will be in the running again, in my opinion.
Ryan Gregson--he has been up and down since last year's injuries, but the Aussie youngster is uber-talented. At his peak, he will make the final and be there at the end.
Andrew Wheating--unfortunately, he's been nursing yet another injury (plantar fascitis that nearly cost him a spot on the team), but he's the most talented of all. Tactically, he's dreadful, always running out in lanes two and three, forcing himself to run much longer races than his competitors. But if the foot allows good training, and he can finally figure out the tactics, he could make a miracle run for the gold.
Ross Murray--love the young Brit, not the least because he's hysterical and never seems to take anything seriously. He's a massive talent who is coming off years of injuries and running stunning times. His recent second place finish in the last Diamond Leage event was unreal. He smoked an incredibly stacked field. It seems hard to believe, given his youth, inexperience, and injury history, but he could well sneak into the finals. My sleeper pick and personal favorite.
Bustos--the young Spaniard is due for a PR.
Various others.
5K--Galen, Galen, Galen! He's taken American distance running to an entirely new level. One of the absolute MUST WATCH performers.
Cam Levins--his PR's don't suggest he can hang, but given his unreal NCAA senior season, you simply can't count out the Canadian.
10K--did I mention Galen, Galen, Galen?? The oft-injured Tegenkamp and Ritzenhein are also in the mix, as well as Levins. This is another MUST WATCH event. I believe the finals will be Friday (there are no heats).
Steeplechase--Jager!! That's Evan Jager, who gave up the mid distances after years of injuries, took up the steeple, and almost immediately destroyed the US record. The Kenyans are supposed to never lose this event. Well, we'll see about that. Mr. Jager may have other plans.
Those are the events I know best. Perhaps someone else can do the hurdles, jumps, and women's events.