You lost me in your explanation, can you give an example?
If you're asking for guidelines on what a character can push/pull/lift, that is covered in the Core Rules under Carrying Capacity. If you're asking for Strength Check DCs based on weight, I don't know of any but that would be a nice way to see if someone can lift something that's higher than their normal carry weight. Letting the wizard have a Strength check to see if he can lift the boulder off the unconscious fighter.
If you're asking about more off the wall suggestions, like throwing a person (which is always an awesome thing to me), here's an excerpt from an RPG dot net board.
Me?
If for some reason I felt like being rulesy about it:
I'd have said, "What's the load you can lift?"
Ok, page 158 of my PHB (202 of the Pathfinder book) talks about Splash Weapons and targetting, so we'll go with that. Make a Touch Attack against AC 5. If you miss, it scatters like the diagram in the book (sorry Pathfinder, no diagram for you).Range Increment is 10ft. If you feel like being stiff about it, apply another -2 penalty if the load is a Medium one and a -4 penalty if it's a heavy one.
As far as damage to a character is concerned, you could be really stiff-necked and do the falling damage rules. If you want to still do _some_ damage but not be horrific about it, 1 point for every Range Increment traveled.
Going even further with it, depending on the amount of damage the character might be taking, a Reflex save for half damage might be appropriate, although even at my most rulesy I'd consider this to be pointless complication, unless the damage was going to be a significant amount or the player spoke up and asked for it.
In my normal GM mode?
I'd have said, "Rock. Is your BaB above +5? Good, don't need to bother rolling and yeah, you're big enough to toss him. Next?"
I'd do it exactly this way for a friendly. Probably add the throwing character's Str bonus to damage for a Fastball Special kind of attack, if the thrown character is willing to take that much damage as well.
For an unfriendly, I'd use the Move option for Grapple, and give the target the reflexive +4 to escape the grapple before being thrown. If the target is being thrown somewhere truly nasty, I'd probably give it a Reflex save as well.
Mutants and Masterminds, another d20 system, handles it a little differently:
Well, I pulled out Mutants & Masterminds and extrapolated. Here's what I came up with:Characters can throw any object they can lift, up to a heavy load. You cannot throw your maximum load, only drop it adjacent to you. Picking up an object is a move action, while throwing it is a standard action, so it's possible to pick up and throw an object in one round.
The distance you can throw an object is based on its weight and your Strength. You can throw your heavy load 5 feet, which is also the base range for throwing. For every 5 points of Strength you have over the minimum required to lift an object as a heavy load, double the base range.
Improvised thrown objects have a range increment of 10 feet.
So, a Large PC with a 22 Strength wants to throw a 200-pound ally. IIRC, it takes a 15 Strength for 200 pounds to be a heavy load. The Large PC has an equivalent 27 Strength for carrying capacity (IIRC) . That puts the Large PC 10 points over the minimum required to lift the ally as a heavy load. The Large PC can throw his ally 20 feet.
I'm not overly familiar with Mutants and Masterminds, so I'm not sure why there's a discrepancy between "base range for throwing" and "Improvised thrown object range increment", but it seems to me that you could extrapolate some rules from these to cover throwing an enemy or ally. There's a 3.5 feat from Races of Stone called Fling Ally, but you had to be Large to use that anyway.
Clearly I got sidetracked by the idea of throwing people around. Is any of this helpful?
As far as Sundering goes, Strength is already factored into the rules for Sundering. I don't see what more needs to be done in that regard.