They're missing their archives and their domain name, but they're back after several years' downtime:
For those who missed the heyday, Conversatron lets you ask questions of its stable of fictional characters, which includes several from Marathon. Here are some past threads from the Web Archive:
"Which Quake message board linked to you?"
"Can you briefly summarize the plot of the Marathon series?"
"Isn't Durandal just the life of the party?"
"They should be a bit busy..."
"Hey, you can't have Durandal without Tycho..."
"Computer! Engage self-destruct sequence!"
"If one has fame, does one really live forever?"
"I mean, Durandal is quite familiar with orbital bombardment."
"I believe you have me confused with Durandal..."
"If not, I will be forced to....uh......take down your website."
"Don't you mean 'Bartender from Fight Club'?"
Durandal and Dante
(shoots green-clad Marathon Bob)
"...rampant AIs from obsolete Macintosh games tending bar..."
"What?! Marathon isn't obsolete!"
"Hey, look, Tycho and Tycho!"
"...but all the AI's we've got back here are pretty unstable."
"I'm not sure exactly why, but..."