More use of immediate actions in general would be a good things for support types. For instance, take healing. Really, there are three types of healing:
1) Out-of-combat healing. Not exciting, but it doesn't need to be, and for that matter, you really just need a wand and someone who can use it.
2) Critical healing. Stopping someone from dying. This has the potential to be very dramatic, but is currently hard to pull off - you have to buffer people in advance because it's hard to reach them in time.
3) Bonus healing. Pretty much any other healing in combat. You do as much as you're able to without compromising your other goals. Potentially important, but dull - it shouldn't prevent you from doing more interesting things.
And it seems like these could be improved by distinguishing them. Bonus healing could an extra effect of striking a hit, much like the Crusader does now. And critical healing could be based around spells like Close Wounds - immmediate action, ranged, so you can directly administer healing to prevent a death-blow on your allies, at the moment it happens.