InterPoker has 5 points per dollar of bonus, with 1 point for each $1 raked pot, and 0.25 points for $0.25-$0.99 raked pots. At lower limits, this makes the full bonus pretty slow to clear (you can get up to a $90 deposit bonus each month but thats 450 $1 raked hands), and no bonus clears until you have all the points needed, which is a little harsh.
If you want to play low stakes and get a bonus relatively quickly, then it may be worth looking at the likes of Ladbrokes and William Hill
, with their hourly bonuses. There is a site BonusWhores.com which covers the subject pretty well.
I'd recommend checking out the offers and looking for sites which clear the bonus quickly, rather than offering the biggest bonuses.