When I was ordained into the Western Buddhist Order I was given the Sanskrit name Jñānagarbha (and here's a picture of the newly ordained Jñānagarbha from 1998). For the eight or so years after my Ordination that I worked as a ‘professional Buddhist’ (running Buddhist Centres, leading retreats, and teaching) I used this name pretty much exclusively, and even changed my passport and driving licence. When I began working in organisations and started a family of my own I began using my family name again, and now alternate between the two depending on context.
It is pronounced something like N'yah-nuh-garb-huh.
The simple translation that my Preceptor (the person who gave me the name) gave me is ‘filled with knowledge’, although my preferred translation nowadays is ‘he who nurtures wisdom’.
I could probably produce a whole website on the meaning of my name, it’s two parts each allude to a separate school of Buddhist philosophy! Jñāna means knowledge or wisdom, and is a key concept in the Yogachara tradition. Garbha literally means womb or embryo, and links to the Tathagatagarbha (or Buddha Nature) tradition. In terms of practice, it's an ongoing reminder that I need to bring together my intellect and my gut feelings into an integrated whole.
A few reasons come to mind:
People very often ask this question in a slightly confrontational tone, and perhaps this points to the deep issues of identity that we address in Buddhism. The Buddhist tradition explains that one of the main causes of difficulty in our lives is our belief that we have some sort of fixed and unchanging core to our being. If you watch your mind for even a short time, you quickly see that the flow of ideas and emotions is constantly changing, and that it’s impossible to pin down a self that thinks the thoughts or feels the feelings. Anything we can do to open up to a more relaxed and expansive relationship with ourselves, those we meet, and the rest of the universe is immensely helpful.