Yes, Bobal is very very good (a bit on the rustic side, but with definite personality and intensity) and of course Mencía, but that’s no longer that new or rare, in fact it’s gone from cult to trendy I would say. The Society currently does two Mencía, both from Ribeira Sacra, but most Mencía is from Bierzo.
The ones from the Canary Islands are worth checking out - Listán Negro, Listán Blanco, Marmajuelo, Negramoll and Tintilla. Unusual and rare. My guess is that the special characteristics of Canary wines is not so much due to these odd varieties, but to the volcanic soils.
But my prize would go to Callet, from the Balearic island of Mallorca. Callet makes world class wines, notably the incredible Àn (previously known as Ànima Negra, and its more affordable sister wine AN/2 http://www.annegra.com/pages.html) and 4 Kilos (and its sister wine 12 Volts http://4kilos.com/). Callet is often combined with two other indigenous Mallorcan varieties, Mantonegro and Fogoneu. Believe me, these wines are superb, and reflect both terroir and variety.
Sadly the Society doesn’t currently stock any wines from Mallorca. Hint hint @PierreM