Madara Uchiha was the 1st Uchiha as well as the 1st person to ever use the Sharingan and achieve the level of Mangekyou Sharingan.
Known Sharingan Users (that remain alive): Itachi Uchiha, Sasuke Uchiha, Obito Uchiha and Kakashi Hatake.
Sharingan: A blood line power or limit only obtained through blood relation (family),known as the "Copy Wheel Eye" or the "Mirror Wheel Eye" who ever posesses the Sharingan his/her vision dramatically sharpens allowing the user to see even the most insignificant details there for the user is able to immitate or copy his/her opponent's (movements,speech,writingjutsu and so on) thus the name Sharingan,the apperance of the normal Sharingan does not differ amongst the ones who posess it.
Mangekyou Sharingan: A blood line power or limit only obtained through blood relation (family) as well as the copletion of a "special" requirement, knows as The "Kaleidoscope Copy Wheel Eye" which pretty much mean a sharper more amplified version os the normal Sharingan, the Mangekyou Sharingan or MS for short has the ability to greately amplify the powers/jutsu of the normal Sharingan, the Mangekyou Sharingan posesses it's own induvidual shape that is only unique ot it's user, but activating and using the Mangekyou Sharinagn comes with a serious and dangerous side-affect.
There are three "main" Sharingan and MS powers, and Itachi posesses all three of them...
1. MS Tsukuyomi: God of the Moon, The Full moon is usually related to going insane in legends. (Itachi used Tsukiyomi on Sasuke on a full moon night, also used it on Kakashi) ***note: all can be both a Sharingan and MS jutsu***
2. MS Amaterasu: Goddess of the Sun, Teleports things to another dimension by warping the spacetime, leaving a dark fire that will burn for 7 days and 7 nights to destroy the surroundings.(when Itachi and Kisame were running away from Jiraiya and also thats Kakashi's main MS power so far).
3. MS Susanoo: God of the Storm, in the most rescent manga (when Itachi was "crying") it started to rain and then as if on his command it stopped, this power is though to be triggered by imotions, also Kisame mentions how weird it is that it's raining in this part of the land at this time of the year.
Plus 3 additional/minor powers...
1. Telepathy: The ability to communicate with others using only ones mind as well as the ability to control ppl (gen jutsu) also seen when Sasuke goes into Naruto's head and talks to the Kyuubi, as well as when Sasuke controled Manda, and Itachis gen jutsu.
2. Teleportation: The ability to travel through time/space over a great distance with in a "blink of an eye", seen when Sasuke sees Naruto (again)for the 1st time and comes down from the cliff, also when Sasuke was fighting Deidara and appeared behind him and used his chidori, as well as when Kakashi and Itachi use their MS to teleport objects which is a far power powerfull form of teleportation.
3. Insight: The ability of a sharingan user to see through deception as well as the ability to pick up on the smallest details, because of the extremely acute vision they now posess, a sharingan user can see through (clones,transformation's,gen jutsu and so on) as well as the ability to see charka itself, this power has yet to be shown as a MS power but it eventually will be.
***Note: A MS user's "normal" vision gets worse everytime the user uses his/her MS and eventually the user becomes blind, that's why you see Itachi always having his Sharingan active 24/7, not cuz his "normal" vision is all gone but that's how bad it has gotten, as stated by Kakashi.***