Some of my friends speculated that it's from the Sex and the City character, or from the Parokya Ni Edgar vocalist - but that's not really where I got it. My source is a real simpler one.
Back in college, freshman year, there was a batch mate of mine who for some reason thought my real name was Miranda. I have no idea why. It sounded nothing like my name save for the first and last letters. Still I thought it had pretty sound; I remember thinking that it was a pity I didn't own it. The new nickname didn't catch on during my stay in college though, but I kept it in my pocket for future use.
I first employed the moniker Miranda a couple years ago when I needed to name my site on Multiply. Miranda has a nice ring to it, it looks cute when written and it's easy to recall. I've grown to love it ever since.
It also happens to mean something nice (I mean, when choosing a name, might as well get one that has a cool meaning, right?).
In Latin, it could mean wonderful, miraculous, admirable or extraordinary.
In Spanish, it means to see + to walk.
I've also read elsewhere it can mean peace or prosperity.
Miranda was created by Shakespeare for his play "The Tempest" from the feminine form of the Latin 'mirandus' (admirable, lovely), from the verb 'mirari' (to wonder at, to admire). This gives the meaning "she who must be admired".
Miranda is also the name of one of the satellites of Uranus. Though Uranus has 27 known satellites, five are considered major. Miranda is the smallest of these major satellites
So far, several sources agree that it was coined by Shakespeare and was not used as a name until the 20th century. In English-speaking countries it's a girl's name; in Spanish-speaking ones it's a surname. Imagine wearing a name created by Shakespeare.
My only problem with it is that it sounds too Western (or American at least), and if I used it with my surname I kinda think it sounds too artificial, almost porn-star-ish.
But overall I like it. Pretty cool. Right now I'm leaning toward having my name changed to Miranda for good (I mean, after I look into the legalities involved and get enough money to have the change made).