The first hp rolling variant I ever came across was in Empire of the Petal Throne in about 1977 or so.
Each level you rolled all your HD again (including the new one), if your total was higher than before, you got it, otherwise you stayed at the previous level.
The upside of this is that a poor roll at one level doesn't penalise you for the life of the character, and excellent rolls don't give you a boost for ever either - it meant that everyone tended towards the average for their level, but still had the excitement of rolling.
In my current games I use 'roll, minimum of half die size', the other DM uses 'player rolls, they choose to keep it or go with the DMs roll (which they take however low it is)'.
Cheers