Proportional per time period:
Take a time period. (lets say 24 hours)
Then let everybody mine that time period. After that time period you say how many blocks have been found and devide this by the total shares that time period and multiply it by the shares per user.
This has a big benefit to smaller miners because in the current Proportional pools they have no chance of getting any share for the blocks that take less then one minute.
The other benefit is the fact that you would only have to update everyones balance once a day. (or maybe still have some expected payout)
This method also deals with pool hopping.
Not really any better. Actually can be much worse the pool hopping.
So what happens if the pool finds an abnormal number of blocks in the morning. Like 8 blocks in an hour. *COUGH* LOL
What's to stop people from jumping INTO the pool afterwards knowing that they'll probably get a larger proportional amount of coins for the mining they are doing for the rest of the day or whatever payout period is left? If the rest of the day's solves are strictly average, the people that jump in afterwards are reaping the rewards for for where they didn't contribute at all. It's pool hopping but backwards. Completely devastating if multiple pools did this. There's nothing preventing them from jumping into the whatever-the-highest-paying-pool is at that time to 'beat the house'.
Just saying.