I currently have only 3 accessories for my Incredible. A case, a screen protector, and an extended battery. I thought it might be helpful to others to list these here, since I have been using them both for a while, and have been extremely happy.
My case is the Seidio Innocase Active. I love this case. It is essentially 2 cases in one. The inner case is a soft case to absorb impact. The outer case is a hard shell to protect it. The fit is very nice, and it retains the design aspect of the phone. It does make the phone significantly bigger, but in all it’s only like 2mm bigger. The case has a nice slightly tacky feel to it, which makes it “stick” in your hand better.
The screen protector I got is the Zagg Invisible Shield. I’m really not a fan of screen protectors, but I am a fan of my Incredible, and I’d hate to see the screen get scratched up like my BB was. That said, I chose the screen only, since I already have a case covering the rest of my phone that provides impact protection as well. There is no doubt that Zagg makes the best protectors. Watch the videos on their site, and you will be a believer. Application is simple, and unless you look at it from an angle, you’ll forget that it’s there. Some complain about the “orange peel” effect, and it certainly exists. But as I stated, unless you look at it from an unnatural angle, you wont notice.
The battery I use is the Seidio Innocell 1750mAh. I chose this battery because it fits in the phone without needing a modified door. This means it can still fit in any protective case. Some people complain that this battery does not really give you much more than the stock battery. I disagree. When I was completely stock on 2.1, I was getting 12-14hrs on the stock battery under my normal use. With the Seidio, I was getting 16-18hrs stock. When I rooted, and went to froyo, my battery life doubled to an average of 35hrs. So you be the judge.