Abbreviations
Acronyms, Abbreviations, Initials
Texting-text message Shorthand

Anagrams
Anagram Genius
Internet Anagram Server

Answers
afraidtoask.com
AllExperts
Internet FAQ Archives
Junk Science.com
Strange But True
The Straight Dope
Snopes
Answers.com

Calculators
Calculator.com
CostofSex.com
Worldometers-real time
...world statistics
Scientific/Advanced
Body Mass Index
Mortgage

Clocks
Internet Clocks, Counters
...and Countdowns
The Official U.S. Time
Time Ticker

Conversions
Roman Numerial
Online Conversions
...(Just about everything)
Cooking
Common/Ancient/ Greek/
...Roman etc.

Dictionaries (also see Idioms & Slang)
Word Oddities and Trivia
Unofficial Marine Directory
Etymology and History of First
...Names
Deviants Dictionary
Merriam-Webster Dictionary/Thesaurus
No in so many Languages
Onelook Dictionary/Translation
...Service
100 Most Often Mispelled Words
The Skeptics Dictionary
Webopedia-Computer and
...Technology

Encyclopedias
25 Online Sources
Encyclopedia on Death And Dying
Encyclopedia of Philosophy
Symbols.com

Excuses/Lying
How to Detect Lies
The Mother of All Excuses Place
Ending Unending Phone
...Conversations

Helpful Resources
GetHuman
National Do Not Call Registry (USA)

How To/How Things Work
hints-n-tips
Animated Engines
Bad Designs
How- Just About Everything
Unworkable Devices Museum

Idioms & Slang
Urban Dictionary
Office Slang
Idioms and Sayings
Speech Accent Archive
The Racial Slur Database
Word Spy
Internet Slang Dictionry
Probert Encyclopedia-Slang Dictionary

Libraries/Archives
Internet Archive
Web Archive-Wayback Machine
Moving Image Archive
Live Music Archive
Audio Archive
Text Archive
Historical Text Archive
ibibilio-Library and Archive
Internet Public Library
The Oops list-images, video
Library of Congress
Online Libraries