quicksilver has got to be one of the most innovative apps for a while (probably the only thing similar but uncomparable would be enlightenment efm -- no link unfortunately, its historical software), and there are new things i learn about it everyday.
so once in a while, someone asks me for some data that is stored in my address book, like my home phone number. but i never remember it. quicksilver has a way to search your address book and access the contents without actually launching the address book app. so this is how you can quickly paste a phone number or email into any window:
1. Ctrl + Space (or Cmd + Space)
2. Type "AlastairTse" (or any name)
3. Right-Arrow (to access the details of my address book entry)
4. Select the piece of info you want to send
5. Tab (to access the actions)
6. Type "Paste"
and thats it, it'll be directly inserted into whatever app you had open, such as iChat windows, etc.
this is much faster than actually launching address book, finding the entry and then copy/pasting.
You can reply to me about this on Twitter: Tweet to @liquidx