In the jobs I'm applying for, none of them have a contact listed, and I'm unable to identify a hiring manager in any way.
Right now I've got a generic line at the top of the cover letter:
To whom it may concern:
... but I feel like that's way too impersonal and detached, and the websites I've read tend to agree. But I just don't know what to put there, or whether I should just take it out entirely, or what.