Travis--In order to get the mistakes out of new material as I practice it, I discover that I semi-memorize parts of it.Specifically, the places where I keep making mistakes -- e.g., certain measures -- I tend to memorize.Also, fast runs where there's no time to study out the notes by sight reading.I don't know about memorizing entire pieces if you have no reason-- no recital coming up, and so on.It may be more of an investment of time that some pieces would justify.
One of the issues of sight reading is looking down at the keys momentarily to place a hand then looking back at the music. The more you practice this the easier it will become. Just as you have to deal with hand jumps on the keyboard, your eyes have to deal with eye jumps from a bar of music to the keyboard and back to the next bar of music.