Other ways to say "I'm rooting for you?"

What are other ways one can say that have the same meaning as, "I'm rooting for you?"

Some other ways:

• I'm supporting you.
• I'm pulling for you.
• I'll cheer for you.
• I'll barrack for you (Australian).

NOTE: I've just seen the (recent) duplicate of this question, which seems to have been the motivation for putting a bounty on this question. My answer attempts to cover all the most plausible scenarios in which one might use the phrase, but in the context of the other question, it is the third section that's most relevant here.

I think it depends a lot on the context, and in particular whether the speaker is in a position to exert some influence the outcome, or only to hope for the best.

In a position to influence the outcome

If you were heading into a meeting where someone was going to be selected for a job, for instance, and you were going to be part of the discussion, you might say

I'm right behind you

or

You've got my vote

or

I've got your back

Spectator

If you'll be avidly watching but can't hope to have any significant influence (e.g., sports) then you might try

I'll be with you every step of the way

(perhaps a careless promise if it's a marathon...) or

I'll be cheering you on

Away from the action

If you can't even watch, but want to offer what moral support you can, the language again changes. Suppose you were sending someone in for a heart bypass; you could say

I'll be thinking of you

or

You're in my thoughts and prayers

or (if you want to get really sentimental and maybe even slightly creepy)

I'll be holding you in my heart

Conclusion

I've heard I'm rooting for you used in all these contexts. The point is that it's really a vague expression of some kind of unspecified support, and so how it gets cashed out will depend on the nature of the support you can offer.

(There are other meanings, of course. No one has yet mentioned I'm trying to drink your breastmilk or I'm getting low-level access to your phone for you.)