I've made an entire working language (more of a code, really, but language sounds cool) based on circular Gallifreyan in Doctor Who. It has a real structure, but I'm not going to give that away
This one is a symbol I made up for temporal direction. It says 'temporal direction' in the shorthand version of the language at the top, and in the corner is the date (18102011). It's the same symbol for past, present, and future, but rotated a different way for each. (If you rotate it so that the word is real properly, that's the direction it faces for that time. Past, present, and future are written in the shorthand underneath each, respectively.
Let me know what you think! And don't be too harsh.
Disclaimer: I do not own Doctor Who, BBC does. Please don't sue me, I love you.