I came across an interesting article, entitled "Streamers and Indicators" by Brent Postal, in one of my favorite magazines, the American Angler. (I like the on-line edition of the American Angler because they post the entire article on-line and do not use teasers.) The novel approach by Brent is that he prefers to use two indicators, his favorites being cork, and he spaces them about an inch apart.
Brent says "In a two-indicator setup, the one closer to the fly should be smaller than the other. This prevents spooking the fish and makes casting easier with a gradual taper of line, indicators, and weight. This setup also enables me to detect sideways strikes, as not all fish hit bugs directly up- or downstream, and distinguish a strike from drag. A sideways strike will jerk the lower indicator and even make the upper indicator turn or react."
He adds weight as necessary to bring the fly into the proper fishing zone which is in contrast to the approach employed by George Daniel who is the USA Fly Fishing Champion and a member of the Fly Fishing Team USA. George uses a "dropper" technique, meaning his strike indicator is actually a dry fly, from which he has his nymph connected. The dry fly gives the fish a second opportunity to get hooked, while providing the strike indicator function for the nymph.
You can learn more about George's "dropper technique" on the Trout University Blog "Top Nymphing Techniques".