A colleague of mine (Thank you Milan!!!) suggested this link: Pixlr. It's an online photo editor. I think it's a great tool for a quick and on-the-fly photo touch up. It's pretty amazing as it supports layers, levels, and curves though I have not used it very much. I did try to use it on some not-so-old photos that I have taken that I believe were sharp and that have already gone through some post-processing. So, here are some shots of BEFORE and AFTER of the photos done through Pixlr. Personally, I think I have improved the photos a bit.
Did the photos improved or I just overdid it? I feel the new photos had more punch and oompf! By the way, the changes made in Pixlr were 1) Tilt shift, 2) Levels/Curves, and 3) Sharpen.