and regarding lightweight wheels. They only make a difference if you have higly tuned, modified/track car. most of us on here will not notice the difference in wheel weights when driving, but only when picking them up.
This is such a misleading post. Unsprung weight- of the wheels specifically, is the best weight to save on the whole car. Saving unsprung wheel weight is about 4 times as effective as saving sprung weight off the chassis. The spinning wheels have rotational inertia so the weight of them has a profound effect on your braking, acceleration, cornering, gas mileage, and slalom speeds. Lighter wheels also are easier on your wear items like pads, rotors, and bearings.
You don't need to have a highly modded race car to feel the benefits of a lighter wheel at all. Lighter, wider wheels, along with sticky tires is actually one of the first things I would do to a stock civic as the benefits are so great. You can feel the car accelerate faster with them, but the benefits in the corners and braking are a bit more subtle.
Light weight is also not the only concern with wheels. Strength is just as important for peformance driving and equals faster lap times due to less flex. Work, Volk, and Enkei, and BBS for example really focus on strength a lot.
EK9 wheels weigh about 15lbs, and are only 6 inches wide. Most great aftermarket 15" wheels with a wider width of 7" (you shouldn't settle for less because you can fit wider tires on wider wheels) are in the 10lb range. Mid range 15x7" aftermarket wheels are usually in the 12 or 13lb range, like rota slips or Kosei K1's. Even these are better than OEM for performance.
Here's a good thread where I explained the pro's and cons of 15" and 16" wheels, along with a short list of good aftermarket wheels.
http://www.ek9.org/forum/tyre-wheels/1543-slipstream-15-16-a.html
Some of my favorite wheels are-
Enkei RPF1 (15 or 16" depending on brakes)
Volk RE30 (best wheel you can buy)
Volk CE28
Volk TE37
Advan RGII (amazing)
Work Emotion CR Kai (hot)
Regamaster Evo and Spoon SW388
Really take a look at these Gee.
I don't really like the SSR Type C because even though it's a forged wheel, it's susceptible to bending.
These are great all around wheels, I would have specific recommendations if you were building a track, rally, autocross car, ect.