Doesn't anyone own and use a hand plane? If you've got a bowed
or twisted piece of stock - cut it to a shorter length if possible
to do safely and reduce the problem then hand plane it closer
to straight.

If you want to cut a rabbet/rebate on a bowed or crooked piece
- USE a rabbeting/rebating bit - with appropriate bearing - and
a routertable! The bearing will follow the edge - no matter how
bad the piece is bowed or crooked.

If the piece is twisted enough to cause problems ripping -
well you shouldn't be trying to rip it on a table saw - regardless
of how long your fence is, the thickness of your saw blade
or how much horsepower is spinning the blade.

OK - so you can use a sled and maybe some shims to stabilize
the stock to semi-safely rip a piece that doesn't have a flat
face down on the table and a straight edge against the fence
-but why not just prepare your stock correctly?

As note by another poster, the table saw is made to do one
thing - cut straight and parallel to the rip fence in the case
of a ripping operation, and cut straight and square to an
edge if cross cutting - the rip fence should be well out of
the way.

Use the right tool or machine for its intended purpose
and in the name of all that's holy - don't try cutting
circles on a table saw! Coves - maybe.

As for working with wide sheet stock - I've got a sliding table
that'll handle about 50+ inches - with the blade just high
enough for cutting 3/4" ply. I take the fence off the saw
to get it to hell out of the way. Anything more than that gets
cut down to 50" or less with a Clamp N Guide and a circular
saw. With 4x8 sheet goods I want the wood stationary and
the saw moving, not the other way around. MUCH easier
keeping a circular saw against the guide than manhandling
a 4x8 sheet of 3/4" on the table of the table saw - WHILE
keeping one edge against the fence.

charlie b