Continuing with the topic of surprise: I've mentioned before that I see certain thief abilities -- picking pockets, hiding in shadows, moving silently -- as being a matter of surprise. Any character class can pick a pocket, if they surprise their target. This is in contrast to treating thieving abilities as something only thieves can do.
I redesigned the thief class as the trickster in order to roll all the thief abilities into a single level- or HD-based bonus to some save or effects roll; in the case of abilities that can be explained as surprise, thieves add their level to the d6 surprise roll, making it easier for them to surprise a target. If they are unaware of an approaching creature, they likewise add their level to their Wis/3 or Dex/3 rating to see if they can avoid being surprised; this becomes the equivalent of Hear Noise.
This also applies to surprise attacks -- in other words, the backstab. Instead of only thieves being able to backstab, any character can strike a surprised opponent in a vital area. What this means depends on how a GM handles a blow to the vitals: it could be max damage, double rolled damage, or something else. For me, it's 1d6 plus a 0 to 3 bonus based on the target's armor, no attack roll required, plus a Con save to avoid an injury. Tricksters get to add their level bonus to the damage rolled.
In addition, I gave tricksters the ability to re-roll surprise by using misdirection or trickery. This has no effect on initiative or ordinary surprise in an encounter, but it does affect the way thievery and surprise attacks work. An ordinary character only has one chance to surprise an opponent and thus only one chance to filch an item, pick a pocket, or sneak past a guard. In some cases, they can try again -- by going away and coming back later. A trickster, on the other hand, can describe a trick, misdirecting the target, and roll a d6 versus the target's Wis/3 or Dex/3 to see if the trick worked. The trickster adds their level bonus to the roll. The downside is that the trickster has to commit to the action; in the case of picking someone's coin purse, this means that if pretending to bump into the target doesn't work, the target notices the trickster's hand going somewhere it shouldn't be.
I think this makes the re-designed trickster better than the original thief. I've seen many complaints about how ineffectual 1st-level thieves are. Tricksters, in contrast, add +1 to chances to surprise and to damage done in a surprise attack, and have a chance to "backstab" multiple times in combat, if they can come up with enough tricks to pull.