I've been playing with the idea of a 5 level PrC with a d8 HD, BAB progression like a Rogue, a good REF save, 4 skill points per level, the ranger's skill list, and the following abilites:
Foray (yoinked from the Sortier class I linked to above) - Movement is doubled as per Expeditious Retreat for Con Bonus +2/PrC level rounds. 1x a day at 1st, 2x at 3rd, and 3x at 5th.
Cunning Strike (also yoinked from the Sortier Class) - +1d6 damage per strike when opponent is flat-footed/flanked (rules as if per sneak attack) at 2nd Lvl, +2d6 at 4th.
Leaping - at 1st level, all jump calculations are done as if the PC was 2x their actual height.
Superior Leaping - at 3rd level, all jump calculations are done as if the PC was 3x their actual height.
Run-By Attack - At 2nd lvl, the PC may make a full attack action while moving his base speed. However, the following strictures apply: all attacks follow the iterative pattern, no more than one attack may be made per opponent (even if the # of iterative attacks is greater than the # of opponents available), and AoOs are incurred as normal for movement through an opponents threat range.
Improved Run-By Attack - At 5th level, the PC can combine a Run-By Attack with Spring Attack, selecting one attack he makes during his Run-By Attack as the Spring Attack (and provoking no AoOs from that opponent).
I toyed with the idea of making Cunning Strike useable only on the first strike against a particular opponent in a melee - think that would be better?
And, I think it goes without saying that I've never created a PrC like this before - I have the sneaking suspiscion that it might be overpowered. Please let me know if I missed anything!