I was looking for a good overview article that explained the process of password hashing and I found Password Encryption, Hashing, Salting Explained which was a pretty good run down.
On a related note I reread the Wikipedia page on HMAC.
I was writing a shell script and I wanted to change directory. But before I changed directory I wanted to get the absolute path to a file relative to the current directory so that I could access the file again later. I learned that you can do this in Bash with the readlink facility, passing in the -f command line switch, i.e.:
$ readlink -f ./some/path
Found a list of MySQL Encryption and Compression Functions today. Handy.