Send to Kindle: This is a web browser plugin for Chrome and Firefox. With it, you can beam an entire web page, stripped of ads, to a Kindle or Kindle app for Android and Apple devices for your reading pleasure.
Pocket: Similar to Send to Kindle but it allows you to send stories by simply emailing a link to a web page. The same can be done by Send to Kindle but it's approach is much clunkier.
Scribd: Trying to read a PDF on an eReader can become quite a mess. This free app for Android and Apple devices gives PDF documents a graceful, intuitive interface that allows for search and zoom, as well as thumbnails, and in landscape mode, displays two open pages just like an old-fashioned book does.