If you wanted to you could look at your wallet.dat in a hex editor to see its contents. In theory you could memorize, but it is mostly impractical. You could print it off and have a small book.
Please look at the date - it's posted more then 1 year ago.
See
https://en.bitcoin.it/wiki/BrainwalletAm I not allowed to post in old threads? (or is it discouraged?) I thought the topic was interesting, bringing your wallet.dat out of the digital world.
You're not forbidden to post in old threads. However, in terms of forum etiquette, it's generally discouraged to 'necro-bump' old threads. Make a new thread to discuss the matter, if you would.
For some reading about bringing the wallet.dat out of the digital world, I suggest you take a look at this article :
http://bitcoinmagazine.net/brain-wallets-the-what-and-the-how/No need to hex edit your wallet.dat as it contains a lot more stuff then your privatekeys.