Daytime things to do in Cali
I'm remembering a few options now. Kilometer 18 is a nice place to visit if you want to get away from the heat in Cali. It's just outside Cali up in the mountains. You'll find good food from vendors/restaurants, the scenery is great if you like mountains, and the temp is about 10 degrees cooler. Just tell the taxi driver Kilometer 18 and they'll know what you mean.
There's the famous Chipchape mall and I also like Jardin Plaza (in the South of Cali), Cosmo Centro (good place for watching/picking-up women), and Palmetto Mall (free wireless internet in food court).
Horseback riding is very common and cheap around Cali.
If you like eating Cholados and would like to visit a nearby city, try Jamundi (where there is a lot of horseback riding too). It's about 30 minutes from the center of Cali.
If your considering investing in Colombia, you can kill time and maybe find a good investment by touring some of the many new condos and houses they are building (mostly in the South of Cali).
Ok, most of these things are pretty boring, but that's all I've come-up with on my visits to Cali. At least the nights are fun.