As istrasci says, can be a rather formal word to use. But it also has uses outside of the super formal ceremonial use - you still hear it fairly often in announcements, as in those you would hear in an ad or department store.
One common use is with a noun that ends with 中
You've probably heard this in an ad before:
I just saw this when watching a comedy show when the lead character is doing nothing:
Also I have heard in this use case when some status is being reported:
This can also be totally informal such as:
You can also say 只今気づいた but my gut feeling is that you can't add the 面白いこと in there without being awkward, even though it doesn't seem to break any grammatical rules. I don't have anything to back this up other than most of the 只今 cases I've heard have been short examples with just the verb or a noun. Please correct me if I am wrong.