osx - How to display a text file within Safari that doesn't have the .txt extension?

Is there a way to have safari 4 on Mac OS X to reload a web page every N minutes on a per tab basis?

Just use a bookmarklet(a chunk of JavaScript that you can add to your bookmarks). Here's one that I found ages ago and it's served me well:

javascript:(function(p){open('','',p).document.write('%3Cbody%20id=1%3E%3Cnobr%20id=2%3E%3C/nobr%3E%3Chr%3E%3Cnobr%20id=3%3E%3C/nobr%3E%3Chr%3E%3Ca%20href=%22#%22onclick=%22return!(c=t)%22%3EForce%3C/a%3E%3Cscript%3Efunction%20i(n){return%20d.getElementById(n)}function%20z(){c+=0.2;if(c%3E=t){c=0;e.location=u;r++}x()}function%20x(){s=t-Math.floor(c);m=Math.floor(s/60);s-=m*60;i(1).style.backgroundColor=(r==0||c/t%3E2/3?%22fcc%22:c/t%3C1/3?%22cfc%22:%22ffc%22);i(2).innerHTML=%22Reloads:%20%22+r;i(3).innerHTML=%22Time:%20%22+m+%22:%22+(s%3C10?%220%22+s:s)}c=r=0;d=document;e=opener.top;u=prompt(%22URL%22,e.location.href);t=u?prompt(%22Seconds%22,60):0;setInterval(%22z()%22,200);if(!t){window.close()}%3C/script%3E%3C/body%3E')})('status=0,scrollbars=0,width=100,height=115,left=1,top=1')

And here's an edited version of this bookmarklet that removes the URL prompt and just uses the URL of the current tab:

javascript:(function(p){open('','',p).document.write('%3Cbody%20id=1%3E%3Cnobr%20id=2%3E%3C/nobr%3E%3Chr%3E%3Cnobr%20id=3%3E%3C/nobr%3E%3Chr%3E%3Ca%20href=%22#%22onclick=%22return!(c=t)%22%3EForce%3C/a%3E%3Cscript%3Efunction%20i(n){return%20d.getElementById(n)}function%20z(){c+=0.2;if(c%3E=t){c=0;e.location=u;r++}x()}function%20x(){s=t-Math.floor(c);m=Math.floor(s/60);s-=m*60;i(1).style.backgroundColor=(r==0||c/t%3E2/3?%22fcc%22:c/t%3C1/3?%22cfc%22:%22ffc%22);i(2).innerHTML=%22Reloads:%20%22+r;i(3).innerHTML=%22Time:%20%22+m+%22:%22+(s%3C10?%220%22+s:s)}c=r=0;d=document;e=opener.top;u=e.location.href;t=u?prompt(%22Seconds%22,60):0;setInterval(%22z()%22,200);if(!t){window.close()}%3C/script%3E%3C/body%3E')})('status=0,scrollbars=0,width=100,height=115,left=1,top=1')

Safari Page Monitor.

This configurable AppleScript keeps an eye on one or more web pages through Safari, reloading them at specified intervals and reporting any changes it detects, both verbally and through a session log file.

The developer explains “I wrote this script to keep tabs on my brother’s home page after they had had their first baby and started posting pictures. I remembered a page-monitoring feature in the Classic version of Internet Explorer and decided Safari needed something comparable”.

That link does not seem to work these days...
There is an on-line alternative (unless you want to write the plugin again).

Just be careful how and where you use this.

You can use an AppleScript to do this. Here’s how to reload every open tab every 5 seconds:

tell application "Safari"
    repeat
        repeat with aTab in (every tab of every window)
            set URL of aTab to (URL of aTab)
        end repeat
        delay 5
    end repeat
end tell

You can do some filtering inside the repeat with aTab block to only refresh certain tabs (predicated on the URL, title, etc.).

If you've upgraded to Safari 5 in the meantime, Apple added browser extensions. I made one that does just what you asked.

You can take a look at it here: Auto Refresh

Use Auto Refresh to set Safari to automatically reload on its own. Perfect for web development and monitoring online auctions, announcements and news.