Mathematically *nice* :
http://mathworld.wolfram.com/TitsGroup.html
In ultra-slo motion:
http://birdstuff.blogspot.com/2007/04/great-tits-in-ultra-slow-motion.html
http://www.montereybay.com/creagrus/tits.html
http://birding.about.com/od/birdstitmouse/ig/Titmice-Photos/index.htm