BILL BUXTON

Here is a guy who imagined all that we see today long back....He is the modern day Leonardo...he had talked about MultiTouch long back in Xerox PARC....
Now he is working for microsoft as a principal researcher.
His book Sketching user interfaces...is good...havent read completely though...


you can catch BIll at:

www.billbuxton.com

DONALD NORMAN

He is single handedly GOD of interaction design....his book Design for everyday things( DOET) is a bible of interaction design and i have been following him since a while now......His was the first book i bought through online shopping...but i can say reading DOET i found a way to a place called NID i.e. education in interaction design....Norman has written many other books....few i admire ....like User Centered System Design....his website has loads of knowledge....he was the first person who introduced me to the concept of Affordances....i wish to meet him once in lifetime...


Here are some of his links:

http://www.jnd.org/

http://www.jnd.org/dn.pubs.html

http://en.wikipedia.org/wiki/Donald_Norman

DAN SAFFER

This one is my favourite. .... He is an interaction desigenr from Carnegie mellon....his website is totally informal...but his work is really good....perhaps he was the first one to help me understand interaction design....his sites give a lot of gyaan....and is a must for all designers who want to be interaction designers... he has written few books and is currenlty working for adaptive path ( those guys who invented the AJAX thingie...)
Danny boy you rock.... Hope to work with you once

Here are some of his sites:

http://www.odannyboy.com

http://www.noideasbutinthings.com/ixd/

my personal favorite .....

http://www.odannyboy.com/id/metaphor&IxD.pdf