I chose abilities that I thought would work best in my campaign for my Choose-Your-Own Rogue class. But I thought you might be interested in seeing some other possible abilities I ended up deciding against. I was trying to avoid choices that would override a player's abilities-- so no diplomacy, bluff, intimidate or lying. I was also trying to include abilities that covered the great roguish triumvirate of thief, brigand, and conman. So here are the semifinalists and why they didn't make the cut:
Acrobatics -- Mostly for long jump and tight rope walking, but maybe surviving falls and swinging on things. Climbing walls seems gritty and Swords & Sorcery (hey Conan did it!) in a way that jumping and flipping just doesn't. But if you want something like ninja's in your game you could squeeze wall climbing into this and be good to go.
Appraise-- Know the value of gems, jewelry and other precious items. I smooshed this in with Ancient lore, now that I think of it, it would probably fit better in street lore. The point being, it seems too small of an ability on its own.
Disguise-- Fool even people familiar with you with a modicum of materials and preparation. This just seemed like it would be useful so rarely as not to be worth adding complexity to my ability list.
Forgery-- Exactly reproduce the markings of someone else. Same as above, not useful very often, but you might include this in street lore if you want your rogues writing the princess love poems as the local pig-herder.
Gambling-- Know how to play, and how to win, whether deservedly or not. This just seemed a cheap way to get money, and not really interesting in play: "I'll lose twice then take them for everything." But, on second thought, it could cause problems for PCs. Your call, maybe (Dex/Chr)
Identify-- Know the function and provenance of magic items. I smooshed this in with Ancient Lore. I always liked the Legend Lore ability of bards and thought it was a shame to be hogged by them (and I was trying to become a bard in 1e!), but this kind of lore seem very adventurerish, Cudgel-like.
Mimicry-- Exactly reproduce the sounds and mannerisms of someone you are familiar with. Again, didn't seem like this would come into play that often.
Read Person-- Tell by looking at their clothing, posture, and facial expression, a persons mood and character. This, combined with Mimicry and/or Disguise might be a good addition for the jongleur-type rogue. Or, you could include them all as a grab bag in Minstrelsy, so a player might be more tempted to pick it.
I would caution, if you decide to add your own abilities to the rogue, not to have too many. I tried to keep them to a minimum and I'm still worried the whole Dex/Chr dual-thing might be too fiddly. I mean the point of this blog is supposed to be about doing more with less, to be more minimal. But I suppose this class could keep people from thinking they need several other classes. And if it heads off the need for a full blown skill system, I think that would be worth implementing the Rogue class right there. On minimizing choices, Delta posted about keeping things as close to 7 as possible here.
But hey, it's been a long time since I've been able to DM, you all probably have some great ideas for abilities that players are wanting to do, but you feel would require more knowledge/skill than a normal person would possess. Share them in the comments.