Ever since I learned what continuations are I feel pain whenever I'm writing web apps. Take a look at things like Borges and how simple life gets when you have continuations.
For those of you who don't know what a continuation is - the short answer is that it's an abstraction for the 'rest' of your program. Anyway - they're kind of evil, really powerful - and I want them. :)
I'll admit that I kind of think of Ruby as a red headed step child language next to Python. Well I did anyway. All I'm thinking now is "why the heck can't Python do some of that".
Ok - so Python doesn't really suck - but I really do wish it had continuations. And no - Stackless Python doesn't count. I want all my features in the primary build of Python.