If tourists or businessmen for some reason have to stay overnight in Colón and need a SAFE place to eat, use an ATM machine, stock up on supplies, etc., their best best would be to go to the shopping plaza/cruise ship port Colón 2000. There are two restaurants there (Café Iguana and a Subway), a Super 99 grocery store, a Western Union branch, and an internet café. The main thing to emphasize is that it's 100% safe as long as you stay within the plaza area, there are both private guards and actual Panamanian police watching over it. Also in the back there are some halfway-decent souvenir shops and you can watch boats go by. How dangerous the city itself is so well-known there isn't much I could add to that, but Colón 2000 is at least one area you can breathe easy in and get some errands run if you need to.
A walled compound within Colón, and the second largest free trade zone in the world after Hong Kong. Unfortunately it is not aimed at tourists but to wholesalers, so it's not the shopping paradise you might imagine. Anything bought here is shipped to the airport and can be picked up only when you leave Panama, with the exception of small items you can carry out. If you're a foreign tourist and just buy a bottle of perfume or an iPod or something like that while you're in the Zona Libre, that's fine, but you will NOT be allowed to leave with big bags full of stuff.
Christopher Columbus statue, Christ statue and Virgin Mary statue (both near the Seawall), Shell Monument, Aspinwall Monument, and Monument of the Students' Revolution. Luckily pictures of these can be taken relatively easily, you can even leave your taxi briefly.
Not as impressive as the Miraflores Locks near Panama City, but if you want to see where the ships enter and leave on the Caribbean side as opposed to the Pacific side, here it is. Not bad really, there's a souvenir shop here as well.
Beautiful Catholic church that's worth a picture, but don't leave the taxi and walk around there. Roll down the window and take the picture, then quickly roll it back up again!