I've practiced memorising things and use a standard peg system.  So far I've managed to memorise 2 packs of cards at once.  I've not spent too long trying to master this, but I would love to, especially as my memory is particularly bad!

I've put some documents that I use in the library to the left.  One contains the number system I use, whilst the other contains details of the monarchs of the UK and how I remember them.