I just added a link at the left to Evil Editor, discovered via Miss Snark. Both well worth the reading if you're convinced you MUST do this writing thing. The Evil Editor offers "plot summaries" and terrible query letters restructured/reimagined.
It's no easy thing to distill the plot of your novel to a paragraph or two, enticing the agent or editor without boring, your tone neither boasting nor begging.
I've whittled and whittled on the summary of the novel I'm currently sending around, meanwhile working on another. This one is being difficult. Can't find the right way into it. So I'm writing chapters and sketches til lightning strikes and fuses it into a spectacular form (yeah, right.)