Since making my blog OpenID enabled (using Will Norris' wonderful WordPress OpenID+ plugin), I have been more on the lookout for OpenID-enabled sites. What has become the standard for me now, is if the site does not have OpenID capability, then I'm not interested in registering with the site. There are a few sites that I would love to get involved with, such as AideRSS, but won't because of the lack of an OpenID login. It's funny, as I have plenty of accounts with a number of different services and providers, but since learning about the wonderful ways of OpenID, I am just more reluctant to create an account on a site, if I can't use OpenID.
On the flip side, I am also on the lookout for sites that have OpenID built into their application. As such, I check out what the site is about, and if it is even semi-interesting, I'll create an account using my identity URI, and start going. Some services, such as Zooomr, have a ways to go still, but it's fun to discover these new and unheard of sites, all because I can login with just one account. Very nice.
Then I look at my existing accounts. I see some big name accounts that I hold, such as Google, Technorati, and Ubuntu. I see it as nothing but beneficial for these services to begin implementing OpenID. The code is open, and it is trivial to build the service on top of your existing framework. It does nothing but extend the possibility of increasing the potential number of users on your site.
Of course, I will continue to use and register for the services that are important to me, OpenID or not. Ultimately, I can't have my productivity hindered because of the lack of OpenID in some sites and services. I wouldn't expect anyone else to hinder their productivity. However, if you're a provider of some service, and you're hoping to increase your user base, may I suggest spending one day getting OpenID into your application? Chances are good, that you'll see a surge in registered users and a need to use your service. I could become one such potential user.