The Internet has become a tremendous source of information for actors and other show biz folk, visual artists, musicians and singers, and writers - these are some of the Websites I have found useful:

Actors, Directors, Dancers and Other Show Biz Folk
Visual Artists
Musicians & Singers
Writers

General Services Administration - Primary source for foreign & domestic per diem rates.

Internet Resources for Actors, Directors, Dancers and Other Show Biz Folk

Independent Magazine for Magicians
Playbill Magazine Online
Stage Directions Magazine
Stagebill
Show Business Online
The Internet Theatre Magazine of News and Reviews
Dance Magazine
Dancer Online
Pointe Magazine, Ballet at its Best
The great All Movie Guide on the Web
The American Federation of Television and Radio Artists
Actors' Equity Association
Directors Guild of America
Screen Actors Guild
Filmmaker Magazine
Billboard Talent Net
American Society of Composers, Authors & Publishers
Variety Magazine
Backstage Magazine
Manhattan Association of Cabarets & Clubs
The Hollywood Reporter
Hollywood Creative Directory
Independent Feature Project
National Acadamy of Television Arts & Sciences
Motion Picture Association of America
Academy of Motion Picture Arts & Sciences
The American Film Institute
The Single Best Source of Facts on the Internet
The Musician’s and Performing Artists’ Guide to Successful Touring.  Agent Jeri Goldstein’s excellent site.
TheatreBooks Online
Women’s Project.  Resource for women in theater
Links to performing arts organizations
The US Government Copyright Office
TaxResources - The Internets best single source of tax related links
The Internal Revenue Service
FCIC National Contact Center - Portal to US Government Information
Switchboard.com - Find People, Get Directions, etc.
Yahoo - Huge portal to all sorts of information, get a personal e-mail account and directions to anywhere in the country

Internet Resources for Visual Artists
New York Foundation for the Arts
Passion4art Website
Art Access Website
ArtNetwork
Art on the Net
ArtSource Website
Resource Library Magazine Listing of Art Museums
The Official Gallery Guide Website
Home of "absolutearts.com"
ARTnews Magazine
The Artchive
Art Calendar Magazine - Business Magazine for Visual Artists
The Museums Website
The Virtual Library Museums Page
Photo Insider Magazine
Graphics Artist Guild
Art Business News
ArtBusiness.Com
The Business of Art
Art Support.
News & Blog items on the business of street painting
Buy & sell stock photography – free membership
Dan Heller.com. A lot of info on the business of photography
independent reviews of photographic equipment, extensive articles, tips & teaching
TaxResources - The Internets best single source of tax related links
The Internal Revenue Service
FCIC National Contact Center - Portal to US Government Information
Switchboard.com - Find People, Get Directions, etc.
The Single Best Source of Facts on the Internet
The US Government Copyright Office

Internet Resources for Musicians & Singers
Bostons Premier Voice Studio - Jeanne Deva Voice Studio of Boston
Billboard Magazine
Music Maker Publications Online
Professional Sound Magazine Online
Live Sound International
Recording Industry Association of America
Billboard Talent Net
Broadcast Music, Inc.
Audio Engineering Society
American Federation of Musicians
CMJ New Music Report Website
American Songwriter Magazine
Copyright Society of USA
Music Business Directory
Association for Independent Music
Music Publishers Association
The Songwriters Guild
National Music Publishers Association
The Musician’s and Performing Artists’ Guide to Successful Touring. Agent Jeri Goldstein’s excellent site.
RecordLabelResource.com. Resource for starting/maintaining independent record labels.
Music Business Solutions
Musicians Contact Service. Connecting musicians & singers to paying gigs.
Just Plain Folks. Music community networking resource.
MusicDish. E-journal of the online/digital music industry.
Film Score Monthly
Film Music Magazine
American Society of Composers, Authors & Publishers
TaxResources - The Internets best single source of tax related links
The Internal Revenue Service
FCIC National Contact Center - Portal to US Government Information
Switchboard.com - Find People, Get Directions, etc.
The Single Best Source of Facts on the Internet
The All Music Guide on the Web
The Concert Hotwire - touring info on the Web
The Ultimate Band List on the Web
The US Government Copyright Office

Internet Resources for Writers
The Writers Web Site - great source for links, particularly for screenwriters
National Writers Union
Publishing Law Center
The Writer's Resource Center
The American Society of Composers, Authors, and Publishers
Writers Guild of America
The Writers Write Resource
The American Booksellers Association
The American Society of Journalists and Authors
The National Association of Authors and Publishers
The Authors Guild
The Editorial Freelancers Association
The Dramatists Guild
Bookwire.com
The National Writers Association
PEN's official web site
The Small Publishers, Artists and Writers Network
The Society of Professional Journalists
The Single Best Source of Facts on the Internet
The US Government Copyright Office
Writers Digest
Forwriters.com. Huge collection of links for writers.
Right-Writing. Advice, links, articles compiled by agent/editor/writer W. T. Whalen.
National Writing Project
Smart Writers.com
Poets & Writers. The nation’s largest non-profit for creative writers; contests, grants, awards, job listings, etc.
The International Association of Media Tie-in Writers. For writers using existing movie, TV, book, game & cartoon characters.
TaxResources - The Internets best single source of tax related links
The Internal Revenue Service
FCIC National Contact Center - Portal to US Government Information
Switchboard.com - Find People, Get Directions, etc.
Writers Guild of America
Text and Academic Authors Association (TAA)