I like using my ereader for things other than books, but aside from Instapaper, converting regular files into ereader format is more hassle than it's worth. Now Amazon's making it easier to send non-book files to your Kindle.
Send to Kindle is a new plugin that lets you send a file right to your Kindle right from the Print menu. You can also store stuff in your Kindle Library to download later, which is nice if you don't want to spam hundreds of files onto your reader, but want access to your junk. Mac support is coming, but it's just for Windows right now.