The definitive source for file extension info..

http://www.fileinfo.net/

Tools 2 track free books (source: NetSpeak)

Oreilly open book
Creative common's licence
Book:"Introduction to Economic Analysis"
Internet text archive

Blogs on Free text books:
Text book revolution

Free computer & IT books

Free Tech books

one can use blogsearch for searching blogs containing e-books.
we can use 'inurl' and 'intitle' for efficient searching of such stuff in google search string...
tinyurl

E-books links

http://lab.lpicn.org/pub/books/
http://www.unix.org.ua/orelly/
http://www.thefreecountry.com/documentation/onlinecpp.shtml
http://www.ingenieriauai.com.ar/eBooks/

Computer and other stuff

computer dictionary
http://www.computeruser.com/resources/dictionary/
http://www.about.com/
http://www.howstuffworks.com/
http://www.whatis.com/
http://www.freeprogrammingresources.com/

Puzzles...

http://www.chennaivision.com/sudoku/
http://www.websudoku.com/

http://www.creativepuzzels.nl/spel/speel1/frameng.htm
http://hlavolamy.szm.sk/brainteasers/links-puzzles.htm
http://www.topcoder.com/

All Telugu links (movies/songs/magazines/news etc...)

Devotional songs
http://www.coolgoose.com
http://as01.coolgoose.com/music/category.php?id=10390

Old telugu songs
http://www.oldtelugusongs.com/cgi-bin/search/search.pl
New telugu songs
http://www.raaga.com/
http://www.musicmazaa.com/telugu/
http://www.teluguone.com/cinima/audio/index.jsp
http://www.telugufm.com/
http://www.ramaneeya.com/
http://www.telugubiz.net/


Movie downloads
http://www.andhra-bazar.com/forum/

Others
http://www.teluguwebsite.com/
http://www.teluguone.com/

www.andhravilas.com
www.andhraconnections.com
www.greatandhra.com
www.idlebrain.com
http://andhraguyz.com/
http://www.vendithera.com/
http://www.teluguclips.blogspot.com/
http://www.onlinetelugumovies.com/
http://www.greatandhra.com/

Blogs
Telugutanam
Telugu bloggers