I´m really into the math-rock genre and I have a lot of favorite bands because of this genere. I think I will go with Piglet, they play very close to jazz, have very technical sounds and rhythms. It´s very enjoyble. Here you go http://www.youtube.com/watch?v=OllEOofj4O8 Battles is a close second, they are experimental math-rock using weird sounds that carry out through out the song. It´s fucking weird, here you go http://www.youtube.com/watch?v=hiWpP_dO_Ho
I don´t think there really is a connection. I read somewhere that when the music started coming out, music blogs thought the music sounded very mathematical and complicated so they started calling it that. Heres the wiki page which talks about how the bands use different time signatures and such. http://en.wikipedia.org/wiki/Math_rock
Battles wouldn't be a band that '"nobody knows about." Gloss Drop peaked at 98 on the Billboard 200, and both of the albums I remember being mentioned as some of the best albums of the year.
You´re right, it´s probably because none of my friends know them and whenever there´s an opportunity to mention them I take it.