This is a cool idea for a hack, Jordeh, but unless it does something I'm not aware of I think the viewposts.php is unnecessary. The search.php can be used to find your threads and unanswered threads like so:
Unanswered Threads:
Code:
search.php?do=process&replyless=1&replylimit=0&dontcache=1
Threads you've started:
Code:
search.php?do=process&showposts=0&starteronly=1&exactname=1&searchuser=$bbuserinfo[username]
Unfortunately without the need for that file, this hack is really a template mod.