I am going to vent.
I absolutely hate writing cover letters. We must apply for so many jobs, and every time we are expected to write an individualized letter explaining just how much we love the position. The thing is, I really don't care. I just need a job. Okay? I just need 1/500 to hit. Does anyone have time to research each firm? Not really. We just bull and they know it. Oh sometimes we really want a job. But you can't just apply for those jobs or you could end up living with your parents. I'd just like to write:
Advocate, Trivium, and All -
Yours is a universal lament, shared by just about everyone who's ever needed a job.
Okay . . . venting done?
Now for the good/bad news. The good news (and sorry to get all grandpa-ish on you), but cover letters are so alarmingly easy now as compared to what they were before. Remember typewriters? Remember manual typewriters? Remember manual typewriters without correction tape? Remember re-typing EACH LETTER if there was just ONE mistake? So, if that helps, Word makes this task really a rather formulaic one.
The good news, following that, is that cover letters are meant to look good. They're not read for literature. They're often not read at all. But that doesn't mean they're not important. The trick is that when you actually do land that interview, that cover letter becomes part of the view of you. So, it needs to look very, very good.
As to examples, they're out there no doubt. But you don't need them. Again, these are there to look good. So, if you're using an example, it's for a professional letter. The words are (almost) less important than how it looks. Do not fight this. Do not go "modern." Traditional is the world of law. So traditional is the world of your cover letter.
Create and maintain a clear system for keeping copies of your cover letters. (This is exactly the skill in the practice of law too.) Modify each to fit the particulars of that firm. Absolutely no "To Whom it May Concern." Ever. If you can't find A name, don't send the letter. Don't cheat, but that doesn't mean you can't be a bit generic. They know the drill. They want to know that you can write and present a decent, basic letter. (There's more on these various points in a book, Insider's Guide to Getting a Big Firm Job, which, in my opinion, speaks to all jobs, or perhaps even to non-BigLaw jobs all the moreso.)
Hope this helps,