Me again! I forgot to mention that they sometimes call these groups "Student Corporations".
I found this page for you:
http://www.lu.lv/e_strukt/citas/spk.html
which is "The Convent Of Students' Sororities of Latvia"
and this is the homepage for Ventonia:
http://www.venta.vzd.org.lv/~diks/ventonia/fb.htm
(sorry, it is all in Latvian, which I don't speak)
here is a homepage for "Fraternitas Lettica"
http://www.tech.swh.lv/~au/fratlett/
Homepage for "Fraternitas Metropolitana":
http://come.to/metropolitana/
and a general webpage of student groups of which I found many of the above links!
http://www.latnet.lv/WWWsites/societ...ons_groups.htm
I hope that this was interesting for you.