That Orthanc power would be more suitable if it was named "Saruman of Many Colours" or "Saruman Ring Maker". I prefer the colour one, but I know that's been used before, hence why I suggested the ring maker.
As for more ideas...I can't think of any atm. If you were asking for ideas for Gondor/Rohan you'd be bombarded by a huge list right about now, but I don't have many ideas for the evil sides, except maybe expanding on the Dunlander/Easterling/Haradrim influence.
Hmmm. I like "Saruman Ring Maker", it has a nice ring to it.
As far as other ideas go: You could possibly add some sort of scout unit for quicker map domination/expansion early on in games (but I reckon doing things like that dangerously affects the balance of the game).
In my mod, Isengard can build a "Dunlend Camp" at economy plots as well as the usual lumber/meat pits. From there you can obviously recruit Dunlend Raiders.
Also, I would consider changing Ugluks "Supper" power name to "Orc-Draught" (which in the books is the substance used by him to give merry and pippin a boost whilst running across the country). I think that fits in nicely with his heal ability.
Just some food for thought!