My new rig has an intel i5-2500k, a radeon 6850, 8gb ddr3, etc. all your standard stuff. But it only came with 1 case fan (120mm exhaust fan) and I'm worried about the airflow inside the case. Would you recommend I buy another 2 120mm fans (one for the front for an intake fan, and another on the side panel, unsure about direction of airflow on this fan right now). The CPU is water-cooled so that isn't really an issue, and I'm also considering purchasing a ram-cooler.
Coolermaster Elite 310 (cheap, I know, but it gets the job done)
Adding a 120mm front intake is a good idea.
As for a side fan idk you could experiment.
In my personal experience side intake fans add more dust then cooling.
A 6850 isn't a hot card.
As christop mentioned ram coolers are totally unnecessary.(looks only imo)
If your GFX card is running cooly then the side door fan is superfluous. If you put in a exhaust fan on the side panel, it will cause cross currents and may be counterproductive for cooling. Try with the bottom/front intake fan first and see if it provides sufficient cooling.
My cas has 6 intake fans (5x 140mm plus 1x 120mm) and 4 exhaust fans (2x 140mm, 1x 120mm, and 1x80mm). As davcom pointed out, dust can also generate problems. I placed organza fabric in the side fans to prevend dust to get inside the case. It doesn´t look any good, but reduces the dust intaken http://en.wikipedia.org/wiki/Organza