I guess this list is mainly for fun, since the developers have a lot of work to do already.
1. Pure rogue can add intelligence modifier to AC (dodge AC) while not using armor or shield. Up to +1 dodge AC from intelligence for every 5 rogue levels. Idea borrowed from Duelist prestige class.
2. Pure rogue gets a spell sequencer. Useful since you can use wands/rods/scrolls on them. Cannot be dropped of course.
3. Pure rogue gets a magic bag with 100% weight reduction. Cannot be dropped.
4. Dispell traps? Not sure if its possible, but it'd be really cool.
5. Twice a day the pure rogue can stir up dust cloud that blinds anyone who enters it.
6. Free ferry and dragon rides if pure rogue has Silver Palm feat.
7. The pure rogue can set an alarm system. If a PC walks on it, the rogue is notified of who walked on it. Useful for relic and city defense.
8. Pure rogue can install ballistas.
Perhaps based on Craft Weapon skill.9. Pure rogue can attempt to steal a relic from another player holding a relic via pick pocket.
10. If a pure rogue has Defensive Roll, and makes his defensive roll save, he also receives 5%-10% of his max hp. Even though Defensive Roll works unlimited times a day, this can be once per day.
11. Pure rogue gets a chance at completely dodging a Bigby's spell if he has Epic Dodge. Chance could be a percentage equal to his level.
12. Blinding Speed is better for pure rogues. Lasts 3 rounds per level. Maybe even an extra 10%-20% faster.
13. The pure rogue can use a token which zones him to a secret room once per day. Perhaps even a time limit of 30-60 seconds he can be in the room. Good for escaping fights... at least temporarily. And yes, other pure rogues can go there to hunt him down. No relics allowed there. Also, perhaps there can be 5 of these rooms, and the pure rogue goes to a random one.
14. Pure rogue can act as a diviner. Can use token once every 10 minutes (real world time) to find where relics are. Perhaps put a UMD check on it.
15. Slippery Mind gives a bonus to will save as well for pure rogues. Maybe +1 per 10 levels.
16. Unlawful pure rogues can use poisons (like Blackguards and Assassins hopefully someday). Perhaps immunity to poisons too.
17. Teleport traps. The pure rogue can set traps that, if another player walks on them, forces them to make a saving throw against all three types of saves (Will, Fortitude, and Reflex). If they fail two of the three, or all three, they get teleported to an assigned map for people with bad saving throws.
18. Pure rogue can attempt to trip opponent (knockdown) for 1 round per 10 rogue levels. Opponent must make a reflex save. For example, opponent might have to make a reflex saves vs. (rogue's dex modifier * 2) + 5. Once or twice per day. Edit: DC of 20 + dex modifier would be easier.
19. Pure rogue can bypass warnings that relic is being raided if Rogue has Stealthy feat. Server only shouts when relic is actually taken, and only if no other players are in relic room.
