I started to leave this as a comment of my last post, but then it seemed to be getting to long (who's the babbler?).
On an ideal day I have the homework answers on the overhead (which I turn on before the class starts for the early arrivers). The minute the bell rings, I set the 5 minute timer, and they have until the beeps to correct their papers in a different color. I grade on completion because I think homework is their time to practice. I also walk around during this time to make sure no one is blatantly copying only. I also grade on work shown and header (name, date, page and problem #s listed, corrections, attempt of all problems).
During the 5 minutes, they can also ask each other or me questions. Then I turn off the overhead, and ask for more questions. I answer the popular questions (5 more minutes). If I don't cover their particular question another 5 minutes, I tell them to mark their questions very visibly on their papers, and I'll answer them when I'm checking their papers later (out of class in any pockets of time I find).
I have my student aid (or me) stamp the papers in some goofy rubber stamp. This way later on if I've accidently marked them a zero, they can prove they've turned in their paper. And visa versa, if they claim they had already turned in their papers, I can check for a stamp. I also go through each paper and check for my list of homework musts (see above) and enter the grades.
It's been the case lately that MOST of the time it doesn't take the full 10 minutes. This has been a great improvement over the BT (before timer) days when they dawdled getting out their materials and talking to their friends and then "wait! wait! I'm not finished correcting" while everyone else was politely and patiently waiting because they had done what they were supposed to do. The timer seems to focus them and curb their overchatting, and they're motivated to correct since they know they're graded on corrections.
I don't know if it's an ideal system (I still spend too much cherished time carefully going over the papers for header, attempt, questions, and maybe I'm not catching all the copying), but it seems to work best for me so far. I also figure that if someone is not using the system correctly (copying, etc), they'll pay for it on tests and such when they don't know the material.