The following is a method which I am starting to use in an attempt to increase awareness during the day.

The Idea: Play a note on some instrument (or pitch pipe, anything that makes a consistent pitch), and remember the pitch which it makes for as long as you possibly can. Keep it in your mind constantly, and if you think you have lost the note, check it again with the instrument. The key to making this actually work for lucid dreaming is to associate that awareness of pitch with awareness of state of consciousness. If you know the pitch, you should know whether you are dreaming or not. Whenever the pitch comes into your mind, do some kind of reality check, physical or mental.

These are the pros and cons I currently believe the technique possesses:
Pros:
-Easy to learn
-You can know almost definitely (unless you have perfect pitch) whether or not you have lost awareness for a significant amount of time because you will probably not remember the correct pitch.
-It is a type of awareness that, with practice, does not seriously interfere with other mental tasks (I am writing this thread while remembering the pitch).
-If you can recognize or figure out intervals, then remembering a C will allow you to, with practice, identify or hum any note you want, essentially perfect pitch as long as you have the note in your head.

Cons:
-Can be interrupted by other random pitches/songs if you aren't careful.
-Knowing a pitch is not a reality check in itself, so it will only help if it either increases your awareness or is associated with a reality check.
-Could be more difficult for non-musical people (not necessarily, just a possibility).

I am not saying that it is any better than being aware of gravity or anything else, but I feel that this will be worth a try for people, including me. Input and feedback are appreciated!