(Plug) Campaign Length, and how to accept and handle the fact that some players aren't always available.

I'm going to start with a link to a podcast I like, and a number of you may already listen to:  Fear the Boot Episode 306 . It's a good discussion (IMO) about stories and the length of RPG campaigns.  I'm curious to know if if anybody here has played campaigns on Roll20 to an ending.  How as a GM do you work to keep your players interested, and coming?  How do you handle player absences?   Do you think campaigns can even be played to an ending over the web? Yes, I'm looking for ideas and a good discussion, but this is totally also to plug a podcast I enjoy.

Fear the boot is awesome. I've got every last episode on my hard drive... except maybe a couple interviews and the like. I had the opportunity the other day to make reference to their  Nazi Zombie Bugbears mp3 , which is still funny. Based on a contest they had a while back. Good stuff. As for dealing with players who aren't there every game, I either have them stand there drooling and doing nothing, continue a very basic strategy (ie: fighters fight most obvious opponents, etc) or have them 'they went home and will be back later' simply not in the game at all.