I ascended Tigermen, Merfolk, and Gnomes to civ status, though the files are now on a long since lost USB drive.
Merfolk were just me twiddling with the system to see what I could accomplish. Making them actually live in the oceans proved impossible, and they were a pain in Fortress Mode (they'd pathfind through water, then stop when they went through due to "Dangerous Terrain," forcing me to mark all water as Restricted), but it was more about experimentation than anything.
Tigermen were supposed to hold the place Dig Deeper Orcs do now (I'd not yet discovered Dig Deeper), but due to me giving them Proud Warrior Race type ethics, instead of Raving Bloody Barbarian ones, they weren't nearly as wantonly aggressive as I'd hoped.
Hill Gnomes were supposed to be a "Challenge Mode" race, basically nerfed dwarves. Had to make special equipment for them, to deal with their sub-Dwarvern size, and they got no damblock or ability to start with advanced metal or underground plants, but I let them access Good plants/animals/wood (gotta love Sunberries and Feather Trees) to help them out. Mostly, it worked, but in one of my test games, they slaughtered the tentacle demon ruling the nearby Goblin fortress early on. The Gobbos converted, or may have been converted by force (the historical record is unclear) to worshiping a Gnomish god of hospitality (one of their favored spheres). Actually, I think I'll re-mod them in again...