I'm sure it's possible but can't quite figure it out. I want an NPC to do an OpenBrowser command, with a specified URL, on a Player.

How do I pass the URL to the OpenBrowser command VIA the Dialog?

How do I tell it to do it on a specfied player?

THanks!

The openbrowser command uses targeting to determine the player to open the browser to. To automatically have it make the invoking player the target you would need to use the 'self' modifier which is one of the standard RunUO command modifiers.
This is true for all commands that require targeting.
So an entry like this would work.

COMMAND/self OB runuo.com

Unfortunately, the command is invoked by the triggering player and so it will check the access restrictions for the command against that player. Since OB is a GM command, it probably wont let you do it for anyone other than a GM.

I am planning on adding a BROWSER keyword to add more general support for this.