http://www.hardcasual.net/2009/11/21/surprisingly-optimistic-things-written-on-the-left-4-dead-2-safe-room-walls/
I'll stick 'em up here, but I didn't write 'em. For the record.
“haven’t you guys seen 28 days later? they live at the end”
Scott, 26
Safe Room 2, Dark Carnival
“Lucy if you read this, I’m probably in the Bahamas drinking cocktails and repopulating the planet.”
Jeff, 42
Safe Room 3, Hard Rain
“All this running’s really sculpting my glutes. Every survivor I meet compliments my ass. Maybe I shouldn’t have married so young. Maybe Dave’s death and undeath is just like God’s plan for me to get laid more. I feel 10 years younger!”
The new and improved Leah, 34
Safe Room 2, Dead Center
“maybe being a zombie feels like being on cocaine. man, i miss cocaine.”
Lindsay, 22
Safe Room 3, Hard Rain
“call 555-3940 for as good a time you can have now that everyone close to you is gone.”
Ramona, 24 – Safe Room 2, Dead Center
“i’m sure some scientists somewhere (in China?) are working on a cure and are gonna find it right before we really really REALLY need it. i know i always found my car keys two seconds before i was going to be late for work.”
Allen, 31 – Safe Room 1, Dead Center
“If anyone sees a man in a Disneyland 25th anniversary jacket, that’s my husband Kevin. Don’t shoot him. Last I saw him he was being clawed in the face by a witch, but I have this feeling he’s still going strong. He has a way with women.”
Penny, 45 – Safe Room 4, The Parish
“don’t worry everyone, we’ll make it through this. ‘it’s not until you lose everything that you are free to do anything.’ Fight Club said that.’”
Jake, 18 – Safe Room 3, Swamp Fever
“this will make an awesome movie some day!!! (too bad Will Smith is dead)”
Derrick, 17 – Safe Room 2, The Parish
“Safe Room 3 has the tastiest brains in the city.”
Joe, The Literate, Critical Thinking Zombie – Safe Room 3, Swamp Fever
I found some of them rather amusing, suspect none of them are there (given they're from a parody site), but would giggle manically if they were. Other recent posts there are funny too!