Vigor is extremely useful as a stamina based HoT (Heal over time). It's actually the best one you'll find in the game. Caltrops is also extremely useful. It has a large radius, slows targets inside it and deals damage over time.
Proxy det is helpful to magicka builds for taking out large groups (be it mobs or other players).
So yep, there's definitely some really useful abilities in the alliance skill lines. Go get 'em!