There were plans to launch a VASIMIR Ion drive for testing - The ISS was the only thing in space with enough electrical power to test it.
Apparently NASA lost interest around 2015.
I think I read something about assembling a manned mars ship out of re-used ISS or new ISS-like parts, but I can't recall where, or if the proposal was serious.
It’d need additional radiation shielding to operate for long periods outside Earth’s magnetosphere. The Lunar Gateway modules are a reasonable blueprint for this.
Also, even with the ISS’s power budget, the VASIMR module wouldn’t operate continuously. The plan was to charge it and then run it for short 15 minute periods. It could operate for longer if it took more power from the ISS. It seems they are considering other options for a flight demonstration.
Apparently NASA lost interest around 2015.
I think I read something about assembling a manned mars ship out of re-used ISS or new ISS-like parts, but I can't recall where, or if the proposal was serious.