It would be useful to be able to pipe text (either a selection or all of it) through an external command. For example, I use Ruby's RedCloth (Textile for Ruby) quite a lot for doing quick markup. It would be wildly cool if I could just type directly into WeBuilder, select the text, hit a combo to pipe the text through RedCloth and have the result dumped back in WeBuilder. This is of course a simple example - with this piping functionality, people could create some really powerful text processing scripts using PHP, Ruby, Perl, Python or whatever. It's almost like a simple plugin system.
Charles