level announcements

I would like to see them. Gives a sense of achievement and encouragement to other players.

Sounds good to me, a simple world announcement once a player reaches certain milestones

Even a private announcement would be nice so I can see when I've levelled up. Seems like there's one for Aura level, but not other skills?

Personally I quite like how Drakor does it where every time you level up, you get an option to post a message to Clan or World chat (or both or neither). The benefits of this over an automatic announcement are:

• More private people can post only to their clan, and more public ones can post to the world.
• Assuming these announcements can be turned off like chat channels, more active people can keep them on for both, less active people can only read their clan's.
• When doing high-exp actions and gaining several levels in a few minutes, some players might not want to spam all of the levels.
• Actively posting lets a user post the level-up message when they're at their keyboard and ready to bask in congratulations.
• This lets players decide for themselves what an important milestone is to them. For some, it might be every level; for others, it might be a round number like every 5 or 10 levels; for others still, it might be whenever they unlock a new action.
• It has more "weight" than an automatic message. With an automatic message, there will be a lot of announcements for people who aren't active in chat, so many will quickly learn to tune these announcements out. With an active message, people can use their judgment and only post when they specifically want to post it - like with any other chat message.