I swear the road is full of 300s and Chargers these days. What are the visual differences in these vehicles? The Jeep is obvious to me. I have an especially hard time making out the 300 SRT8 from the front hard.
Please enlighten me. :D

The Only difference i can see is through the SRT8 Badge on the 300C and charger and Obviously from there performance.

The Charger SRT8 has a hood scoop. Like Uae said, the 300 SRT8 has a different grill/lower front fascia. Both have different (larger) wheels over the non-SRT vehicles.

All SRT models have a slight protrusion under their chin.

The charger is a bit easier also due to the SRT clip on badge as well.

I'm p[retty sure the 300 SRT8 has red brake calipers as well... Many non SRT8 300 owners like to upgrade the rims, but the red calipers are a dead give away.

Charger SRT8-Red calipers
Magnum SRT8-Red calipers
300C SRT8-Silver calipers
GCSRT8-Black calipers

I had a 300C 5.7 and now have an SRT8. The differences on the 300C are subtle between the two. Besides the previously mentioned silver calipers and lower front facia, Some of the others include:

5.7's have chrome mirrors, door handles, and bumper caps. SRT8's are all body color.

5.7's have 18's. SRT8's have 20's

SRT8's have a body color rear spoiler. The only 5.7's that have a rear spoiler from the factory are those with the "SRT Design Group" option.

5.7's have rolled tips on the exhaust. SRT8's have an intercooled type of design.

SRT8's do not have any 300C badging in the rear.

SRT8's have brake cooling ducts eminating from the front facia next to the fog lights. (take a close up look, you'll see them). 5.7 cars do not have them.

The differences on the 300C's are very subtle. It takes a little bit to notice them. That is why I like it and decided that my wife could not have all the fun in her car!