Set Your Sitecore Source Field to a Relative Path

Just some quick hits, took me a little while to figure out how to do this so I thought I'd post.  Let's say you have a multilist field, and you want the source to be a sibling folder, in this case one that's called "tags".  Here's what you set the source for that multilist field to:

query:../tags/*

Let's say you have a dropdownlist and you want the source to be the parent of your current item, but you want to specify the template. This is how you do it:

query:../*[@@templateid='{templateId}']

Make sure templateid is written all lower-case.  That's it.  Quick like a bunny cuz I have to rush back to work.