Sean,
First off, this is a VERY common occurrence among right-handed drummers everywhere. It's a matter of really working that left hand. Sometimes even practicing in the early stages more intensively with your left than with your right, to even them out.
Strengthening your hands - wow, that's a topic I'm sure everyone and their mom's dog is going to have an opinion on. What works for me is:
1. BIGGER STICKS - I usually use 5A's when playing so I practice with VIC FIRTH Thomas Lang Signature sticks, which makes everything harder because the sticks are beefier, thereby strengthening your hands. Practice singles, doubles, and then double that from 50 - 250 bpm. There you have a roll, folks. IF you can go faster, by all means Mike Mangini, do it!
2. CHOKING UP - I also choke way up on the stick, right near the tip, and use all fingers to move the bulk of the stick upwards at a high rate of speed, increasing the weight on my fingers, strenghtening them. (I'm from the school of thought that doesn't want carpal tunnel at the age of 30 so I use only fingers)
3. STICKWEIGHTS - Includes a variation of choking up on the stick, you can place them in differing places on the stick for differing weight resistance. you can buy these little beauties from PROMARK.
http://www.promark.com/products/view.cfm?product_id=b252157c-a61a-47af-82ea-adcf5bc4daaa
They are also useful for double-kick strenghening.
4. ENDURANCE PRACTICING - Depending on the style of music you play, it can be challenging keeping good technique and delivering a loud, consistent sound if that's what you're after. One tip I have heard and have put into practice is that when you feel your grip start to tighten because you are getting tired, just choke up a little on the stick and you will have more leverage. So practice it before it ever becomes an issue in a live or recording situation.
Hope that helps!
_________________
Skill tempered with relevance and simplicity.