I’m not religious, and I have friends who aren’t religious. I usually say “bless you” when people sneeze, just to be polite. However, one of my friends sneezed once and, after my “bless you,” commented, “I don’t like that. It smacks of religious overtones.” “Go to hell!” I replied, smiling. From now on I tell my athiest friends to “go to hell” after they sneeze. It’s quite entertaining. 
My wife says Gesundheit. I usually say “Bless you”, or sometimes (as we said in Spanish class) “Salud!” (Health)
A friend of mine says (among friends… usually), “Satan welcomes you!” 
I say “Gesundheit”, myself. I thought it was more common in American communities with a lot of German immigrants, like where I grew up; is that the perception of other posters or is it a fairly widely known word?
I knew this girl in college, we were in a history class together, who had a funny ritual about sneezing. She would sneeze twice, sort of half stifling it, and then say this certain phrase. It was especially entertaining in the middle of the final exam…
::Total silence::
“Knee! Knee!..Bless me!”
::Total silence::
I always enjoy just looking at them in amazement and exclaiming “Get the f*ck out of here!” like they’d just said something bizarre. It’s pretty good for impregnating a pause.
It’s common in France to just ignore sneezing but one sometimes hears “À vos souhaits!” (ah VOW s(ou)way). [The familiar (i.e., non formal) equivalents is “À tes souhaits!” (ah TAY s(ou)way)]
A former French teacher claims the proper response to this (i.e., by the sneezer) is “À vos amours!” (ah VOW saMOOR) [“À tes amours!” (ah TAY saMOOR)]
“À vos/tes souhaits”: To your wishes
“À vos/tes amours”: To your loves
[Beavis]
Heh, heh, heh. He sneezed. Yeah. Heheheheheh. Cool.
[/Beavis]
“Good One!”
-me
I say, “Whoa!”, and back away.
heheehhe…thanks for the entertaining answers guys. I don’t know if I found one that i would use, but def. entertainign
Cheers
Well, I usually say “Salud,” which as mentioned before, is Spanish for “Health”. I think the Italian is pretty similar. If you feel stupid with a foreign word, you could just try saying someting like “Good Health!” but then, I’d feel pretty stupid saying that, so I guess it’s really whatever you’re comfortable with.
LOL
I love that one!
When people sneeze around me I normally don’t say anything. Just like I don’t say anything when they fart, cough, hicup, burp or any of the other crazy stuff the body does.
I though “gesundheit” was pretty much well-engrained in the American lexicon. I can’t think of one person who’d be perplexed by the word. I swear the word was used in Saturday-morning cartoons and the like. 'Course when I was growing up, I heard it pronounced more like “gazootight” rather then “geh-zoond-height.”
Skerri - why would your friend get angry using the German now-pretty-much-English “Gesundheit”? Too Teutocentric?
The words “bless you” really don’t confer on me the religious connotations. For me the phrase has passed into idiom, and have as much religious significance as “good luck” or “well done!” Webster’s unabridged 2nd entry for this word is “to make happy, blithsome or joyous; …” And that’s the context in which I think of this word. Of course, YMMV