if i could travel back in time, i'd twist the arms of early html specifiers to create a way to use something akin to the <a> element to submit form data, so early search engines wouldn't have had to implement the lame heuristic of avoiding pages with a ? in the url because it was the only way to implement a text link to an unsafe operation. (and you don't usually want search engines crawling around doing things that change your site. like the robot who voted down posts on glenn fleishman's weblog.)

i'd also whisper “use web as the hostname” in the ear of the first person that used the barely-pronouncable www. (assuming, of course, i didn't get to the people who developed urls first, and convinced them that having the scheme be part of the name lookup would be a good idea so that http://example.com/ could be directed to the right host at the dns level without telnet://example.com/ having to be the same host.)

yes, the sorts of things i'd do with access to time travel include some fairly modest things. it's annoying when things that were so right (like the overall web architecture) have these annoying burrs that are still annoying all these years later.