Are there any ways to allow a druid to use Predator's Flurry on a charge?
Is there a page out there that documents ways to use powers as part of a charge (or as a MBA etc)?
No, there are no feats exist to allow you to make Predator's Flurry instead of an MBA during a charge attack.
4e is premised on Simple Core rules, many exceptions. In 4e, only being able to make MBAs as part of a charge is the general rule. Specific powers with the line:
can be used as part of a charge attack. Alternatively feats may allow specific powers to be used in place of an MBA during a charge. For example, Precision Ambush Style allows the fighter to use Footwork Lure (an at-will attack power) as part of an MBA. Likewise, Power of Skill can allow an Avenger to use Overwhelming Strike in place of any MBA. Outside of a power saying it can be used to charge or a feat saying a power can be used to charge there is no way to use At-wills in place of MBAs.
Having looked through the online compendium, there aren't any feats like the two I gave as examples for the druid class.
To be able to use this as a MBA you would need something that allows you to use it as a melee basic attack. Typically this is accomplished using a feat, but this only works for a few powers and this is not one of them.
I don't think there is any way to use this as a MBA. I've thumbed through the charge optimization stuff that wizards has out, and none of it does this specific conversion. This power can't even become an MBA for an opportunity attack (far easier if this were an at-will).
No, you cannot use Predator's Flurry on a charge.
Unless a power specifically says it counts as a melee basic attack or can be used in place of an MBA when charging, there's generally no way to use it on a charge.
There are a very few ways to change a few specific powers so that they can be used on a charge, but those are almost all for specific at-wills of divine & martial classes or for specific encounter powers of martial classes.
Allowing something to be used on a charge is not something the primal power source does well (everything the barbarian should be able to charge with can already be charged with, and none of the other primal classes specialize in charging), and is very hard to do with encounter powers for anybody. Even just being able to use an at-will power on a charge that you normally couldn't use is a Big Deal(TM) for some classes, given how much charge optimization dominates striker builds.