Native American wisdom relates to the feather as an embodiment of bird spirit. For example, eagle feathers had special meaning and were given to warriors as a tremendous honor of bravery and courage. It indicated nobility of the heart and allowed the recipient to take flight easily on journeying (both in a spiritual sense and a life-journey sense). Feathers in Native American minds as well as many other cultures deals with communication. Feathers are often viewed as messages from the spirit world, and feather tattoos will convey powerful ideals about holy exchange. Indeed, many schools of thought believe seeing feathers on our path is a direct message from a loved one who has transitioned into the spirit side of life (deceased).
In Celtic symbolism and myth, Morrigan wore an intricate cloak of feathers (typically raven feathers) as a means to transform into a bird. Legend indicates her ability to shift into bird form allowed her higher reasoning, and a "bird's eye view" into spiritual realms. In this form she could also easily travel the earth and spy about on people of interest to her motives.
If Egyptology is your thing, then a feather tattoo might symbolize the wisdom of the goddess Maat who is a matriarchal figure of truth and justice. During mummification, Anubis and Maat compared the weight of heart against the weight of the feather to determine the purity of the soul (and eligibility for the entrance into the Afterlife without consequence). If the heart was light as a feather, the soul was deemed pure and the spirit could move freely into further evolution.
In this way, feathers are also status symbols in many cultures. Plumed knights, feathered headdresses, feathered cloaks - these are all symbolic of higher class of people - usually for the brave hearted, or the spiritual master.
A more expanded view of feather tattoos deal with thought, intellect and the higher mind. This is because feathers (birds) are associated with air, the skies, and the heavens. This also forms a logical connection with dreams, inspiration, spiritual ascension and higher intelligence.