"Tama" can mean a lot of things. A lot of people associate it with "Tama-Kame" the turtle from Love
Hina - the "Kame" is turtle. I actually took the name from the cat in Fushigi Yuugi. "Tama" is
supposedly a common, all-purpose cat name. Anyhow, "Tama" can mean treasure, ball, etc and I've had a few
people play jokes on that nick (like when Dom gave me a pair of nerf balls and said "Here TamaTama!" Although
that was also because he said we needed more "balls" in the shoujo panel speakers, which was unaccountably
highly female for the first time in the history of AX...)
(edit)
By the way, I use an IME editor but if you don't have one and don't want to install one, you can usually use
Jeffrey's J/E dictionary (http://dict.regex.info/cgi-bin/j-e) to look up characters if you know the
romanji for it. It'll give you the character in shift-jis or other encoding which you can copy/paste into Word or
Photoshop.