while(<DATA>){
  s#(https?://\S+?)(\.?\s)#<a href="$1">$1</a>$2#igs;
  print;
}
__DATA__
Students can activate their UMSIS userids on-line by filling out and submitting the form at https://umsis.miami.edu/sign-up.
...which can be obtained via the web at http://www.miami.edu/it-forms/.