I am sure almost all of us have an endless number of accounts on different sites including several email accounts, social websites accounts, blogs, online shopping carts and so on.

I always find it difficult to remember all the usernames and passwords that I use (especially when I come back from holidays :))

Openid.net offers the possibility for using a single user account for all the websites you use.

Websites like Yahoo, WordPress, AOL, Blogger, Flickr, Orange, Technorati offers an openid account.
This means that you may already have an openid account!