title attribute, which shows as "hover text" in certain browsers, and the
target attribute are part of the rich text format (RTF) area hyperlink options. :-)
Additionally you can allow CSS styles for certain RTF fields, which you could template or convert to a different output.
For additional RTF features, you could consider a GUI extension (Anguilla framework).
Where possible, though, I would template certain attributes, possibly pulling the information from the linked item. For example, links to a certain "pop-up" Component might automatically set a certain type of
Target attribute or add the CSS and script to create a pop-up.
Update: examples of Rich Text Format Area GUI extensions:
You'll need to consider or create an extension for both the Content Manager Explorer and Experience Manager.
The alternative to a GUI extension would be a Custom URL. This would be a "lighter" approach at offering editors custom functionality. They would click on a field's description field and a pop-up page you create will let them set and change values.
Either approach requires at least some HTML and client-side development. GUI Extensions are more of a framework than API. If you extend the UI to make this easier for editors, I would recommend one more step to offer good defaults, selectable options, and some contraints. For example, it'll probably be easier to choose from a set of pop-up sizes rather than enter height and width each time.