Lots of good comments already - the Stewart tip should gain you quite a bit.
Just one further note: in the salary cap (or gm-style) leagues I've been in, the winning strategy has often been to use all
available pitcher trades to switch around the highest-valued pitchers, as you suggested you would do with Pedro and Schilling. Apart from making sense in terms of points gained (since your trades are bringing you the highest possible return in terms of value and games pitched), this tactic should also bring in lots of extra cash, since many other players will be using it. In order to exploit this fully, though, you might consider using the Unit every once in a while.
The exception here is of course when there's a bandwagon to jump on in order to make a profit. I assume Weaver will have jumped quite a bit since the trade; Denny Neagle might be next, if he does in fact go to Pittsburgh. In those cases, making a profit is probably more important than getting an extra start from an ace.