This is what I am going with as a tank, you may prefer to move certain points around a bit. I will probably end up changing it a bit when I get to 50 once I have had the chance to settle on a rotation. ATM I am making the tree in a way to help levelling but once I don't have to worry about that I will change it to make tanking more efficient.
Rydel on the other hand has the
following build on his knight tank, and is a successful tank (even though he has decided to get a Vanguard instead).
As far as DPS goes, Rage works well for PvP and can be useful for PvE. Not sure of how pure Vengeance fares but it sure makes you jump a round a lot.
Also ask some Guardians in the guild and you should be able to apply their trees to a Juggernaut build since it's the same. (Unless there are bugs but those only harm Republics anyway =P)