Necroing to put some fun links, but anyway, it looks there are a few people who are still using the T-34.
First off, I should note that this is all coming from this website:
https://wwiiafterwwii.wordpress.com/
Which has a lot of fun and kind of random posts about various pieces of WW2 gear that was being used after V-J Day (some times long after, some times until now)
Wikipedia gives the sourceless list for current operators as Mali, Somalia, Syria, Yemen, and North Korea. I think we can cross Mali and Somalia off the list, as I can't find anything that says they've actually been seen in those two countries recently (and Mali had to dig pretty hard to hold out against Islamist attacks, so I think we would have. For Somalia, I just can't believe we haven't seen them after 25 years of war. There may be some derelicts hanging around in the country side). And surprisingly (considering everything else that showed up, including a bunch of StG-44s and German WW2 era artillery)...T-34s did not make an appearance in
Syria. They have been seen in action in Yemen, but it's not sure if any are still doing so.
North Korea: as noted, had at least one operational T-34 filmed in an exercise in 2013. I'd feel comfortable thinking they probably have more in reserve of unknown quality/condition. Additionally, a number of their patrol craft and gunboats for their Navy use T-34 (and IS-2/3) turrets in lieu of actual naval guns onboard...which, totally counts for the purpose of this discussion, I guess?
Vietnam: moved the last of their units into reserve in 2010, apparently. With one big exception: some are located in their garrisons in the Spratly Islands, and the Vietnamese lack the logistical capability to move them, so have left them there in operational order.
There are probably a few other countries which have some (different sources give different lists), but that appears to be a decent one as of 2017.