Access to servers, SaaS apps, crucial infrastructure software. There are tons of things that need to be accessed by people in the organisation. Although, in many cases, there is an option to create new users but sometimes it's not and often, creating new users is more of a hassle every time someone needs access.
How does your company deal with giving and managing access?
For servers we use LDAP, so you just SSH to a machine and it creates an account if one doesn't exist. It authenticates against AD every time, so if an account is disabled there, their access to all servers is instantly revoked. You can still use SSH keys so you don't need your password every time.
Internal web applications (mainly Rails) are backed by LDAP too, but also support NTLM SSO for Windows uses (so they only need to enter their password once when they log-in to their machine). Not everyone uses Windows (or is part of the domain), so we use CAS on top of that to make switching between applications transparent for everyone.
We don't really use any external services that we need to share passwords for.