The Cosmic Microwave Background: The CMB surface of last scattering occured at approximatley 1066 which is the year that historians consdier the begining of the Middle Ages (the years just prior being the late Dark Ages). Historically 1066 was the year of the Battle of Hastings and the ensuing Norman conquest of England. In the case of cosmology 1066 coresponds to the begining of the cosmological dark ages.
The mass ratio of a proton to an electron: The actual ratio of a proton to electron mass is 1836.153. The Battle of the Alamo was 1836. This trick works best if you are from Texas.
Euler's number: e is 2.7 1828 1828 I wrote it with the spaces between the 1828's because many people remember the 2.7. And 1828 is one year after Beethoven died. This trick works best if you know your classical composers.
This memory trick using historical dates seems strange even to me; if anything the physical constants actually helped me remember the history dates, but either way I remembered. Memory tricks can be powerful tools. For example you can memorize nearly 4000 digits of π with a mnemonic technique, but the most powerful memory enhancing approach is certainly the method of loci.
Be sure and watch the second part that teaches you the link memory technique.