I randomly happened across Ariel (aka the Tea Fairy) last night. Started off as a mission USS. I dropped in to investigate and was offered a mission to source Tea for some station. I've had a similar encounter with the Mineral Magpie some time back. Not seen any of the Seeking ones in quite a while though.
Unfortunately the Seeking Weapons beacons have been removed some time ago, not sure about the other types but I haven't seen them since last year. I used to use the Seeking Weapons sites to hunt T9 for mats in Anarchy systems. It used to be the only reliable way to get the trading ship mats in sufficient quantities and I would rationalize that I was hunting down arms dealers as an alternative to blowing up regular traders at Nav beacons. Now you can just look for Combat Aftermath USSs instead and don't have to blow up traders at all but I still wish the Seeking Weapons sites were available.
I miss the seeking weapons too. They added a nice extra to smuggling content and side portion of game play around civil wars. They paid pretty well too without being over the top.