I've only found one through referral and the jury's still out on that one.
I took a strange route - I knew I wanted an older home, but I also knew I didn't know what I needed to be wary of. I found a home inspector who specialized in older homes and asked him if he knew a realtor who would know what he/she was looking at in an older home. I ended up being happier with my realtor than in my loan officer or my home inspector.
My realtor is an exclusive buyer's agent, which means that he doesn't list houses himself. He also is independent, so it's not like he's working out of an office with buddies who are listing houses. I decided that he was the one when I asked him my prepared questions and he didn't try to BS me - for instance, I asked what the sale price to list price ratio he typically got was and he didn't try to sell me on the idea that he could get me unrealistically low prices for a house. He basically went into current market conditions and talked about how there was a lot of variance between different houses - some being listed at prices that were appropriate and some that really weren't, and that the range I should look in should be pretty close to the price I was willing to pay and that we'd figure out the comps to make a decision. He also didn't make me sign an agreement that I would buy through him or face a penalty.
I think you should definitely interview and figure out who you feel most comfortable with. The most important question, imo, is "What happens if I feel that this isn't working out?"
If you're looking in SE Michigan, I'd be happy to refer you to my realtor to see if you click.
Starting Score: EQ 583 TU04 619 EX 592 (lender pull) 2010
I found mines on realtor.com by putting in requests for additional info on the homes I liked.
Cards: Orchard Bank ($1100) | Cap1 Cash Rewards ($2500) | Chase Freedom ($1000) | Best Buy ($2500) | Discover It ($1000) | Barclay Rewards ($2500) | Current scores: EX FAKO: 684, CK TU: 649, FICO EQ: 680, FICO TU: 698, FICO EX: 658 Happy Homeowner Since 2/6/13! 
No, I've never heard of Redfin. I have to check it out. I like the idea of them working for me rather than commission. I searched realtor.com and I found a couple there to call as well. Financial advice comes from my uncle, he's a CPA in another state though. No loan officer yet.
I'm in NC.
We found ours at an open house. We were not even seriously looking but wanted to stop in and check out the home. She roped us in and we love her! She is amazing and extremely proactive. Any time I have a question or feel a little lost, she goes out of her way to bring everything back on track.
I was working out at my gym and I saw this good looking woman that was looking at me. We got to talking over the course of several workouts and she told me that she is a real estate agent. From there it's history.