Vipassana Meditation: The most common meditation technique; focus on your breathing to reboot your brain. If you get a minor high when you stop meditating, you did it correctly.
Meditative Reading: Read a book, but let your mind wander. Will seriously limit your reading speed, but works more as meditation than reading. Helps a lot if you read more cryptic books, like religious texts or ancient philosophy.
Meditative Writing: Write text and reflect on things you write. Simply having a diary can be meditative, some people prefer a learning journal.
Ethereal Meditation: Get tangible but fleeting ideas that float in your mind while laying in bed just about to fall asleep. If you have something on your hand as you fall asleep, dropping it to the floor will wake you up, so you remember what you were thinking about.