Should we memorize scripture?

I have gone through phases in the past about memorizing scripture. I have memorized entire books to just a few select verses. I believe it is a necessary part of spiritual warfare training to memorize. You "memorize" certain dates, names of friends, lines from movies, words to songs, passwords, etc. So, we should and here are a few reasons why

Ephesians 6:17 "Take the helmet of salvation, and the sword of the spirit, which is the word of God"

Christ wielded this sword when dealing with satan. He did not need to look it up. (see Luke 4:1-28)

Psalms 119:11 "I have hidden your word in my heart that I might not sin against you"

Ephesians 5:15 "Be very careful, then, how you live, not as the unwise but as the wise, making the most of every opportunity, because the days are evil. Therefor do not be foolish, but understand what the Lord's will is"

See proverbs 8 and 9 to know what wisdom is.

Psalms 37:31 "The law of his God is in his heart, his feet do not slip"

We are mandated to put on the full armor of Christ, know it in our heart, and be wise.  When I know it by memory, the result is I mediate on it, pray it and attempt to practice it more.  See Cafe655 for John Piper's comments on it.