The golf one sounds easy, but most of those web sites are directly integrated with POS systems. A lot of courses buy it all together as a package. Plus the biggest golf course management software vendor in my area aggregates all the golf courses they serve into a single web site, so you only have one account. Also, as much as I love Open ID, trying to get your average Joe Schmoe golfer to use it is not going to work.
The easiest way for people to remember their logins for sites is not to USE logins. Use EMAIL ADDRESSES instead. Then, if they forget their login, they just enter their email address and it auto-generates a "reset password" link. Open ID is cool and all, but it's nowhere near frictionless enough for average people yet.
I love it because failed logins are minimal and requests to reset password even smaller. (Incidentally, rather than "reset password", I give people auto-login links which are guaranteed to be usable for at least one day, and then pop up a message on login telling them how to change their password. This eliminates any needless copy/pasting and supports my ~10 users who prefer to ALWAYS log in via the forgotten password feature. Hey, two of them paid money, I'm not about to complain.)