A 'real' synopsis (which you'd send to an agent or publisher to summarize the whole book) would go in Query Letter Hell.
What you're talking about, blurbs, are usually not written by the author but by someone at the publisher, sort of teasers to tell a little about the plot, enough to interest a potential reader. Some publishers use quotes from authors to whom the publisher gave advance copies instead or in addition to blurbs.
Maryn, recommending QLH for any of these