Magic of the world is based around everyday objects and activities. No two mages have ever been found to have the same power, although some may be similar or relate, such as thread and clothing, or singing and dancing. It also might be noticed that while telekinesis is not actually ambient magic, it has been discovered that two mages who feel romantic love for each other can speak mind-to-mind; good friends and relatives can usually pick up general emotion from each other.
All magic abilities fall into three categories: Creation/Beginning, Preservation/Middle, and Destruction/End. Think of this either as the triumverate of powers in Hindu myth or as corresponding to Clotho, Lachesis, and Atropos, the three Fates in Greek mytho who spun, measured, and cut the threads of life respectively. As a general rule (it doesn't always hold true), creative magics such as painting fall under "creation" (duh), things that use physical energy and personal talents like song and dance fall under "preservation", and magics that are elemental, use language like spoken word, and magics that channel energy through a source are destructive. The three powers respond respectively to the colors green, yellow, and red.
Most mages also identify more with one element than any other and it usually relates to personality; however, mages are not generally limited to one element unless their power is based off of that element. Mages who fall into the latter category always have greater use of and control of an element than a mage who uses his powers to channel an element. The elements are water/ice, fire, light/day, plant/forest, air, night/dark, lightning, storm, sky, shadow, earth, sun, and moon.
Most mages can read auras in some form or other; some merely see colors, and others see them through their powers (i.e. a thread mage would see auras as thread running through a person).
Magic generally manifests some time during adolescence, usually between the ages of 14-16, though it depends on the person. Occassionally, powerful emotions will cause a mage's powers to bloom into full force where otherwise they'd be latent for years.
Bounds for magical abilities are almost non-existant. They can be anything in the world around you. However, here is a list of some suggestions that Goo and I have brainstormed up:

spoken word
written word
sign language/hand signals

For those characters who work with colors, such as thread or gem mages, here is a list of color correspondences:

Color: Element- Attributes
blue: water, ice, cold- warding, empathy
scarlet: fire- attack, offensive, destruction powers
white : day, light - magic dampening, reflection
green: plant, forest- healing, creation powers
yellow: air- binding, preservation powers
black: night, dark- energy absorption
orange : lightning - communication
purple: storm- telekinesis
indigo: sky- divination
gray: shadow- medium abilities*
brown: earth, stone- grounding
gold: sun- strength, purification
silver: moon- intuition

*medium powers = the ability to see/exorcise spirits