I had the opportunity to make 2 THROB QSOs today. Why? Just because stations were calling and had RSID signal on so I knew it was the THROB mode. Never ever heard any station before in THROB. Now after some searching there seem to be 2 THROB modes, THROB and THROBX. Interesting, but obscure. THROB is a MFSK mode just like JT65 and JT9 and many more. DM780 (HRD digimode software) has a lot on board. A interesting list can be found here, including waterfall pics:
Some inside info on digimodes can be found here:
Although I miss SIM31 in his list. By the way, AC4M tested populair PSK decoding software in several situations:
Of course these are not the only sites about digimodes. But lots can be found. I don't know how many digimodes there are around but shure there are many.
What is the most obscure mode you ever used?
For me it is THROB at the moment, but you never know what I will encounter next time...