LISA
Localization Industry Standards Association
LISA's TMX page
LISA's standards page
LISA's Globalization Insider
LISA is also working on SRX, the segmentation exchange standard and TBX, the terminology exchange standard.
OASIS
Organization for the Advancement of Structured Information Standards
OASIS' XLIFF page
OASIS' XML Daily Newslink
OASIS' Standards page (you may want to take a look at DocBook and OpenDocument)
W3C
World Wide Web Consortium
W3C's Internationalization activity page
W3C's Internationalization Tag Set page
W3C's Translated articles page
WHATWG
Web Hypertext Application Technology Working Group
And while we are at it, something that is likely to appear on your desktops earlier than you think, HTML 5.0