There are a couple of electrodeless lamp technologies out there, some in
production, and some prototyping (the sulfur lamp is in the latter
category). Most of these are better known (and more available) in Europe
than in North America.
Induction lamps are available from Philips, GE, and Intersource Technology.
Philips QL lamps are theoretically available now in North America, but
don't appear in their catalogs, and haven't been marketed here except to
luminaire manufacturers. Luminaires are available in Europe.
GE's Genura lamp has been available for some time in Europe; GE Lighting
was talking about a 1995 introduction for North America, initially
targeting 75 watt R30 retrofits (since these are going away October 31).
Intersource Technology has some products, but apparently none in
distribution yet; they seem to still be talking to luminaire OEMs.
The QL lamps have separate power supplies, CRI >80, efficacy about 65-70
lumens per watt (i.e., comparable to compact fluorescent & MH), and average
rated life about 100,000 hours (don't you love statistical extrapolation?).
The "big" lamps put out 6000 (initial) lumens.
The Genura is packaged as a complete unit with a medium screwbase, slightly
smaller than the R30 it replaces. Its CRI is 82, efficacy a bit lower than
MH (but much higher, of course, than the incandescent it replaces), and
average rated life of 10,000 hours. It puts out 1100 initial lumens.
The induction lamps are in production, and are well received in Europe.
Their power supplies run at 2.65MHz. The QL is FCC certified for
commercial (but not residential) use; the Genura should be certified for
residential use. The induction lamps use RE phosphors, and so can produce
the same flavors of light as compact fluorescents.
The sulfur lamps are still prototypes. Their efficacies are also projected
to be comparable to the compact fluorescents and MH lamps, with life in the
10,000 to 20,000 hour range. The big problem seems to be getting an
affordable, efficient, and most of all reliable microwave source. They are
running at 2.45GHz to take advantage of the components already available
for microwave ovens. There have also been some complaints about the color
rendering of the prototypes.
One should also point out that 5900 watt, 450,000 lumen lamps have limited
applications in residential construction. Make a pretty nice oven, though,
or you could bleach out your carpets to a nice neutral beige.