Probably my 2004 Gmail account, but that’s pushing the definition of “still use somewhat frequently”. I do still have my email forwarded to my current address, but most senders have been updated with my current address.
I lost control of my Hotmail, AIM, ICQ accounts years ago.
95589327 holy shit how is that still in my brain? I have not used this number in... at least 20 years and here it is, more clearly than the phone number I've had for 10 years now.