There have been many options available in the past. This is a list of items readily available.
Option Numero Uno
Moss Dual Headlamp System (Also known as lo-pros)
$490 + S&H
As far as cosmetic changes, this system is considered to be the best performing system out there. I know of know complaints regarding light output. They are a copy of the original KG Works Dual Headlamp System
which is very pricey because it is a JDM product.
Option Numero Dos
AAC Flush Mount headlights
$590 + S&H
This system looks great. The carbon fiber buckets are beautiful and it uses the same lamps as the Moss kit. A lot of research was put into making this a high quality kit as previous kits were sub par. The light output is not as good as the pop-ups because the lights, being tucked in, do not illuminate to the side.
Option Numero Tres
E-Codes
The fancy ones are available from Hella and Cibie
Expect to spend about $80.00 + S&H
This is the most common upgrade as it's the least expensive and comparable to the high output of the Moss kit. However you still have the large barn doors.
Come out to a Wednesday night meet and there are all three kits usually available for you to check out. Titus has the Moss, John Wagliardo has the AAC, and I have some e-codes.
If you are willing to wait a few weeks, I'm replacing my e-codes and I'll be selling them. My e-codes are a generic lens but just as good IMHO as the Hellas, Cibies I've seen.