No cache

whats the meta tag for html files that wont let the browser put them in the cache?

This for expiration:
<META http-equiv="expires" content="Sat, 1 Jan 2000 00:00:00 GMT">

Another way:
<META HTTP-EQUIV="Pragma" CONTENT="no-cache">

Note that some versions of IE cache data anyway (ignoring these tags). I think the expiration method is better, but you can use these in combination.