Discounting acronyms, for words without hyphens that have three consecutive letters, the OED lists these:
For words that have a letter, a hyphen, then that same letter twice repeated, it lists these:
For words where you have the same letter twice, then the hyphen, then that same letter again, it has all these:
ass-ship, ball-less, ball-lightning, ball-like, bee-eater, bell-less, boss-ship, boss-shot, boss-stone, brass-smith, burgess-ship,
call-letter, call-loan, carcass-shell, cell-layer, cell-less, cell-like, cell-lineage, cell-lined, chaff-flower, class-subject, compass-saw,
compass-signal, compass-stock, cross-saddle, cross-sea, cross-section, cross-sectional, cross-sectioning, cross-seizing, cross-sell,
cross-shed, cross-shoot, cross-shot, cross-sleeper, cross-spall, cross-spider, cross-springer, cross-staff, cross-stitch, cross-stone,
cross-street, cuckoo-orchis, cypress-spurge, demigoddess-ship, distress-sale, doll-land, dress-shield, egg-glass, fall-leaf, fall-less,
fee-estate, fee-expectant, frill-lizard, fusee-engine, gall-leaf, gall-less, gill-lamella, gill-less, gill-lid, glass-sand, glass-shaped,
glass-shell, glass-shrimp, glass-slag, glass-snail, glass-snake, glass-soap, glass-sponge, goddess-ship, grass-seeder, grass-siding,
grass-snake, grass-snipe, grass-sparrow, grass-spirit, grass-sponge, grass-spring, head-mistress-ship, ill-less, ill-lived, ill-looking,
ill-lookingness, isinglass-stone, Jaycee-ette, joss-stick, kill-lamb, kiss-sky, knee-elbow position, mastiff-fox, mill-lands, mill-leat,
mill-lodge, miss-stays, mistress-ship, moss-seat, moss-starch, no-see-em, off-faller, off-falling, off-farm, off-field, pass-shooting,
patroness-ship, poss-stick, press-shy, press-stone, press-stud, princess-ship, process-server, puff-fish, quill-less, seamstress-ship,
see-er, see-everything, shell-less, shell-lettuce, shell-lime, skull-less, small-leaved, smell-less, stall-literature, still-liquor,
stress-strain, three-edged, three-eight, till-land, toll-lodge, troll-line, wall-less, wall-lining, wall-lizard, well-laboured,
well-labouring, well-laced, well-laden, well-laid, well-languaged, well-learned, well-leaved, well-led, well-legged, well-lettered,
well-lighted, well-liked, well-liking, well-limbed, well-limned, well-lined, well-lit, well-liveried, well-living, well-loaded, well-lodged,
well-looked, well-looking, well-loved, well-lunged, will-less, will-lessly, witness-stand, zoo-organic
I see a product opportunity here. :)