Spelunky rapidly becomes one of my most favorite games. What I really would like to see are level expansions. Like in Binding of Isaac there is (I think) a 50/50 chance to play either "the basement" or "the cellar" as first level. This applies to all levels. It would be fun, if there were a similar mechanism in Spelunky. It would be really exciting not to know, wich level will come next.
Hopefully the developer considers this idea.
By the way, I bought "Binding of Isaac" three times, just to have the large expansion. Just a hint... ;-)

I too would pay for extra variants on levels and such. I do wonder if there will ever be any extra content for this game other than playable characters. I think I remember reading that Derek Yu wanted to have some DLCs like this, but I can't think of where I heard it.

Even if there aren't, I'm sure we'll see some awesome mods now that the game is here on PC. The classic game had a bunch of cool mods made for it.

Yeah, especially the aspect of randomisation in the game calls for some additional content. For example I would like to see upgrades for the whip, like in the Castlevania games. So if you have luck, you get an upgrade, that helps you fighting the stronger enemies like Anubis. At the current state it is almost impossible to kill him with the whip.

Great, I made a typing error in the topic. I would pay for expansions.