The applications are done. Transcripts are sent. SAT/ACT scores sent. I guess the only thing left to do is to wait... and wait... and wait...

Well, not quite. You can actively wait. Just because the application is sent does not mean it's over. It's not. You have to actively maintain your extracurricular activities as well as your GPA. Don't give up on the project you wanted to pursue just because you think the "college game" is over. Send an update email to the colleges that you are interested in. While you don't want to email the colleges on everything and anything that you've done after the January deadline, you do want to update them on significant achievements since then.

For example, if you finished a research paper, send them an abstract and attach a PDF of the paper. If you performed in a school concert, send in a link to the performance. If you finished a painting, send them a PDF of that, too.

Actively showing interest will reaffirm your interest in the school and they will take note.