dexterseo - When you say "individual keyword categories," but that they're all also "financial services sites," it's not clear how "individual" in fact they are.
It's also not clear where your other inbound links are coming from, what their hosting situation is, etc etc....
How many of each sites inbound links are coming from the same pages?
Are your sites hosted on the same server? On the same class C?
Google has many ways of determining relatedness, but it has seemed to me that when pages are on domains that are sufficiently related, they start to be treated similarly to dupe pages.... not the same thing, exactly... but Google doesn't like strongly related sites to rank for the same search phrase, and they will sometimes arbitrarily choose which site they keep.
I asked a question in this thread that was similar to yours, but maybe different. In part, the difference may depend on what you mean by "promote"...
Safely Crosslinking Sites for Users
Is the "rel nofollow" attribute appropriate?
For the record, as I just posted on another thread, I agree with caveman's suggestion to avoid the "rel nofollow" attribute in this situation.