I know it's kind of silly but I just like my little story. See, my Highrise dropbox is under the name "Highrise". So every time I forward an email to my account I just type hi ! Mail completes the rest... It just feels great, I can manage the biggest part of my work with an application as simple as "hi". :)
For more on how to do this, check out the Highrise and email page at HighriseHQ.com.
Any little thing like this that you like in a 37signals product? Let us know.