I had the bright idea to look for an F96T12/BLB. I didn't know they didn't exist at the time, but thought it would be pretty cool. So that brings up the topic: what are some of the weirdest and rarest lamp types you have heard of? Do you have any cool ideas for lamps that don't exist (yet)? I still think an F96T12/BLB would be awesome.

I would say the most unusual lamp ive seen to date was a UVC germicidal lamp rated at 130w...and it was a PL fluorescent! I remember it clearly even though its been almost 7 years since ive seen it. It was basically a 48" compact fluorescent lamp that was 48" in length with the typical PL tube shape which I believe was T6. And the typical 4-pin 2G11 base with the stamp "HIGH OUTPUT UVC 110w-130w" No brand name from what I saw. The more interesting aspect of it was the application. Several (about 6-8) of these lamps were fitted into quartz sleeves that were inserted into a large filtration system connected to a small lake! The lake was used for culturing the plant, water mint and these lamps sterilized the water of algae blooms and kept the whole lake crystal clear so max sunlight would reach the plants under the surface.

3 way lamps with A19 envelopes in low power ratings like 10W/40W/50W, 20W/55W/75W, etc. for low brightness applications (and 3 way lampholders with separate screw terminals or flying leads for each contact instead of an integrated switch).

7W to 15W GLS lamps with A19 envelopes.

Multiple U bent compact fluorescent lamps with a different color phosphor in each U (such as different white color temperatures or red/green/blue).

Low power (40W or less) lamps in A23/A25/PS25/PS30 envelopes.

Compact fluorescent lamps with an integrated incandescent ballast lamp.

12V PAR38 lamps.

As far as extant lamp types are concerned, I have a 9W Philips SLS lamp that appears to be a 120V version of their PLC compact fluorescent lamps.  The base is marked specialty so it must be some kind of custom or promotional lamp as it is the only one that I have ever seen.

I also have some 18V candelabra base indicator lamps of some sort that I estimate to be of 1930s to 1950s manufacture, possibly General Electric.  They have T4 envelopes and have a rated operating current of 110mA.

The only other rare lamp I can think of is a 1920s A17 envelope 15W lamp.

I own a 30-volt, 10-watt incandescent with a candelabra base. I used to have three. I can't remember what they came from.

Perhaps not rare in Europe, but I have three pastel-colored GE 230-volt, 25-watt incandescents: purple, yellow, and green. I think I had a blue one at one time but I broke it. They're roughly a G14 size with a base larger than candelabra but smaller than intermediate. I don't have a socket for them.

I saw T12 U-bend fluorescents with a 3-inch spacing as opposed to the usual 6-inch in use at the Houston-Hobby airport about 10 years ago. Never seen them used anywhere else since.

F10T5 fluorescents in LOA fixtures.

Daylight incandescent lamps. I mean REAL ones, which have a dark teal color and an actual cool white or daylight color temperature. GE made them until I think the 1960s. The only ones you can get now have a light blue coating and are 3200k or so.

4500k fluorescent lamps. GE and Sylvania made them as the predecessor to cool white, but I don't think anyone makes them now. I've never seen it, myself. Closest I have is my 4300k Norelco F8T5/33.

Finally, I have a circline adapter which takes a 13 watt lamp, seen here. I've never found a replacement lamp for it. It'll be a sad day when it goes EOL. 

I have a NOS Duro Test F30T8 4500 degee bulb I got from Paintballer22.

How about a GE clear 3 way bulb? I have one, a 50-100-150w, specially made for demostration purposes. It was made at the now defunct Winchester Lamp Plant. I also have a Chromalux clear neodymium 3 way bulb made in France, the only production 3 way lamp I am aware of other than the 50-50w and 100-100w marine running lights and some clear hospital bulbs, all of which use 3 way bases.

How about some GE Mazda Daylight Rough Service bulbs? The catalogs I've seen did not list these bulbs, but i have a few. The sleeves are marked "Daylight Rough Service" and they have the blue tinted glass and RS filaments. They must have been a special order.

How about the Derby special 100w bulbs that were used for street lighting in the UK city Derby? They were the oversized PS-80 (about the size of the GE 300w bulbs in the USA) bulbs. An estimated 500 bulbs are believed to be in existence in the world, 20 years after these bulbs were discontinued. In 60 bulb cases, that would be 8-9 cases taking the space of a corner in a garage. Imagine this level of rarity!

How about the ELMA Last specials? They were the last 100 bulbs made in Australia by ELMA before the country lost its bulb making industry, sadly. I was nicely given one by a collector last year.

In the gas discharge category, I have a Champion F40/D daylight fluorescent lamp from around 1943, it originally belonged to late L-G member J-Frog. I also have a GE Type H-2 mercury lamp, which is a 250w medium pressure lamp with no outer bulb and a medium base. It was a rare and short lived lamp. Last of all, I recently acquired two A-H5 lamps, the earliest form of the 250w mercury lamps still made today. The A-H5s I bought are from the 1940s and have T-15 outer bulb envelopes. One is a GE and the other is a Westinghouse.

So far, your posts also mention interesting lamps as well, never seen a F96T12/BLB but Interelectric Corp may have made some.