I think I'd be up for a 20-something pancake for crop-sensors. Maybe like a 24 or 28 with 2.8 or at least maybe a 24/28 2.8 without IS or something like that for when wishing to travel light.
This may seem like an odd suggestion but, consider the M+22mm f/2. It can be had for $319 (on Amazon right now) and probably less if you look around (lowest price was $299). The great appeal of pancakes is the small form factor, well, it doesn't get any smaller than the M+22. Plus, at that price, it's cheaper than a lot of other primes in that focal range and it's FASTER than what you were hoping for by a full stop - not to mention the improvements in the sensor from your T1i.
Just tossing it out there as an option in case you hadn't considered it!
And if you REALLY like the idea, consider a full setup with the 18-55mm IS lens plus 90EX flash - this 4 piece combo can sometimes be had for as little as $400.