For many of my projects, it would be useful to be able to create variables which are available system wide for Record Rules, Page Rules, Equations, Formulae, Filters, Emails and Action Links.
For example, my clients often want to know who has taken a particular action on a record - completed a task, swabbed a patient etc. In some cases this leads to quite a lot of Connections to the user object just from one other object.
So, if we could set variables based on the current user (any field on the user record) that would be incredibly useful.
I can also think of several other situations where more user defined variables would be useful - for example returning to a particular page for a particular record after a process consisting of several pages - here the url of the page could be concatenated with a recordID and then a Submit rule could send the user back there rather than just the parent page or a main page. This type of variable would need to be definable using the equivalent of a Text Formula.