Some of our clients have a LOT of roles, and so we've created a higher level element called Role Groups, which they can use to group roles together, for example "Admin" for all the site admin roles, "Members" for various types of member activity etc.
It's proved very useful for us and we use it on all our sites. It does mean that we have to have our own RoleManager.aspx page, and I've often wondered whether others would find it useful.
We only have it working for SQL Server and I'd need to tidy-up the maintenance of Role Groups, but if others seemed keen I might be tempted to knock it into a shape that could be deployed elsewhere, so let me know what you think...
Image (hopefully) here - https://skydrive.live.com/#cid=9167C4933FDA8BE8&id=9167C4933FDA8BE8%211172
Ian