Each of these commands will run an ad hoc http static server in your current (or specified) directory, available at http://localhost:8000. Use this power wisely.

Discussion on reddit.

Python 2.x

$ python -m SimpleHTTPServer 8000

Python 3.x

$ python -m http.server 8000

Twisted _^(Python)

$ twistd -n web -p 8000 --path .

Or:

$ python -c 'from twisted.web.server import Site; from twisted.web.static import File; from twisted.internet import reactor; reactor.listenTCP(8000, Site(File("."))); reactor.run()'

Depends on Twisted.

Ruby

$ ruby -rwebrick -e'WEBrick::HTTPServer.new(:Port => 8000, :DocumentRoot => Dir.pwd).start'

Credit: Barking Iguana

Ruby 1.9.2+

$ ruby -run -ehttpd . -p8000

Credit: nobu

adsf _^(Ruby)

$ gem install adsf   # install dependency
$ adsf -p 8000

Credit: twome

No directory listings.

Sinatra _^(Ruby)

$ gem install sinatra   # install dependency
$ ruby -rsinatra -e'set :public_folder, "."; set :port, 8000'

No directory listings.

Perl

$ cpan HTTP::Server::Brick   # install dependency
$ perl -MHTTP::Server::Brick -e '$s=HTTP::Server::Brick->new(port=>8000); $s->mount("/"=>{path=>"."}); $s->start'

Credit: Anonymous Monk

Plack _^(Perl)

$ cpan Plack   # install dependency
$ plackup -MPlack::App::Directory -e 'Plack::App::Directory->new(root=>".");' -p 8000

Credit: miyagawa

Mojolicious _^(Perl)

$ cpan Mojolicious::Lite   # install dependency
$ perl -MMojolicious::Lite -MCwd -e 'app->static->paths->[0]=getcwd; app->start' daemon -l http://*:8000

No directory listings.

http-server _^(Node.js)

$ npm install -g http-server   # install dependency
$ http-server -p 8000

Note: This server does funky things with relative paths. For example, if you have a file /tests/index.html, it will load index.html if you go to /test, but will treat relative paths as if they were coming from /.

node-static _^(Node.js)

$ npm install -g node-static   # install dependency
$ static -p 8000

No directory listings.

PHP _{^{(>= 5.4)}}

$ php -S 127.0.0.1:8000

Credit: /u/prawnsalad and MattLicense

No directory listings.

Erlang

$ erl -s inets -eval 'inets:start(httpd,[{server_name,"NAME"},{document_root, "."},{server_root, "."},{port, 8000},{mime_types,[{"html","text/html"},{"htm","text/html"},{"js","text/javascript"},{"css","text/css"},{"gif","image/gif"},{"jpg","image/jpeg"},{"jpeg","image/jpeg"},{"png","image/png"}]}]).'

Credit: nivertech (with the addition of some basic mime types)

No directory listings.

busybox httpd

$ busybox httpd -f -p 8000

Credit: lvm

webfs

$ webfsd -F -p 8000

Depends on webfs.

IIS Express

C:\> "C:\Program Files (x86)\IIS Express\iisexpress.exe" /path:C:\MyWeb /port:8000

Depends on IIS Express.

Credit: /u/fjantomen

No directory listings. /path must be an absolute path. Use Command line instread powershell

Meta

If you have any suggestions, drop them in the comments below or on the reddit discussion. To get on this list, a solution must:

1. serve static files using your current directory (or a specified directory) as the server root,
2. be able to be run with a single, one line command (dependencies are fine if they're a one-time thing),
3. serve basic file types (html, css, js, images) with proper mime types,
4. require no configuration (from files or otherwise) beyond the command itself (no framework-specific servers, etc)
5. must run, or have a mode where it can run, in the foreground (i.e. no daemons)