Oh, its even more fun than that.
Since our classes and/or photowalks can have as many as 75-100 people, I hand out 3 or 4 lists of names and ask people to mark their name off.
Once I get home, I go through all the checkoff lists and click the "good to see you" button on Meetup.com. This way, the only people that still display the "good to see you" buttons are the no-show people. They get switched from "attended" to "noshow" on the edit attendance screen.
As each person is moved from "attended" to "no-show", I right-click on the person's name and open their profile in a new window. Once all the no-shows have been assigned, I then go through all the other windows - one-by-one. If they have no-showed 4 or 5 times, they are sent a polite "feel free to rejoin when your schedule free's up" email, and get the boot.
Otherwise, they get a polite "we missed you tonight" email. This gives folks the option to reply with "My cat died", in which case I reassign them to "absent".
And now you know why I've been trying to automate the process. :)
Joe