Scenario - I wanted to provide an easy download link that can be used to circulate a number of documents to people on a maiing list, with them able to pick and choose which they read. Don't want them to have to login / give passwords, but do want to be able to make it something more than just a simple URL. Don't want to have to write much code either.

Simple solution - require them to add a piece of text as the query string for each item downloaded; if sending out links in am email, that extra text can go into the link. Use mod_rewrite to check for the query string that's required. If it's there, feed the required document, otherwise feed an error page.

Here's my .htaccess file (with the passcode - extra string - altered from the real thing, of course!):

  RewriteEngine Off
  RewriteEngine On
  
  RewriteCond %{QUERY_STRING} (10_per_day)
  RewriteRule ^(.*)$ $1 [L]
  
  RewriteRule ^(.*)$ i.txt

The i.txt file is my error text file; the passcode can be easily changed and since it's a regular expression I can do all sorts of things with it like add alternatives. It would also be a good idea to add this directory to my robots.txt just in case someone publishes a link and passcode on their own page.

P.S. The rather curious off and on for the engine at the start is to prevent the parent directory's mod_rewrite settings percollating down to this directory.
(written 2012-06-05, updated 2012-06-09)

 A607 - Web Application Deployment - Apache httpd mod_rewrite
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  [1006] Apache httpd and Apache Tomcat together tips - (2006-12-24)
  [1009] Passing GET parameters through Apache mod_rewrite - (2006-12-27)
  [1207] Simple but effective use of mod_rewrite (Apache httpd) - (2007-05-27)
  [1376] Choosing between mod_proxy and mod_rewrite - (2007-10-02)
  [1381] Using a MySQL database to control mod_rewrite via PHP - (2007-10-06)
  [1636] What to do if the Home Page is missing - (2008-05-08)
  [1731] Apache httpd, MySQL, PHP - installation procedure - (2008-08-01)
  [1771] More HowTo diagrams - MySQL, Tomcat and Java - (2008-08-24)
  [1778] Pointing all the web pages in a directory at a database - (2008-08-30)
  [1954] mod_rewrite for newcomers - (2008-12-20)
  [2094] If you have a spelling mistake in your URL / page name - (2009-03-21)
  [2555] Bookkeeping - (2009-12-29)
  [2728] Redirecting a home page using mod_rewrite - (2010-04-17)
  [2768] Carrying a long URL around - looking for memorable shorts - (2010-05-17)
  [2773] Dynamically watching your web site via a PHP wrapper - (2010-05-21)
  [2900] Redirecting a page - silent, temporary or permanent? - (2010-08-03)
  [2981] How to set up short and meaningfull alternative URLs - (2010-10-02)
  [3197] Finding and diverting image requests from rogue domains - (2011-03-08)
  [3339] Simplest ever proxy configuration? - (2011-06-28)
  [3568] Telling which ServerAlias your visitor used - useful during merging domains - (2012-01-04)
  [3862] Forwarding a whole domain, except for a few directories - Apache http server - (2012-09-17)

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