In Preview, selecting Rotate from the Tools menu rotates every page of a PDF left or right. This can be a pain if (say) you have a portrait-format brochure which includes one landscape-format map. An undocumented feature, though, is that you can hold Option while selecting Tools » Rotate, and this will rotate the current page only.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20070312031649116