I received an email today from a cousin. It is difficult for me to explain the relationship precisely because:

• her paternal grandfather and my mother's paternal grandfather were brothers.
• her maternal grandmother and my father's paternal grandmother were sisters.
  
• and, one of her great-grandmothers was a sister to my great-great-grandfather.

Needless to say we're related ;-)
Once you get back five generations on her pedigree chart 5 out of 8 names in every generation are also on my pedigree chart!
Double cousins are pretty common for me---which explains why I have one genealogy database instead of several separate ones.
Michael