I'm curious as to whether or not any country has any real plans for a manned mission to Mars. Not a conceptual thing, but real, hard plans. If so, are there any specifics?
I do not know of a country, but Mars One are looking for volunteers to send someone.
Sorry to extend your question to corporations rather than "countries" (assuming government-led).
Laura Seward Forczyk gives one of the better summaries of potential manned Mars missions I've seen lately -- especially concerning Mars One. In summary, Mars One is a gimmick and no one is going to Mars in the next 15 years and probably longer. Most of what you hear otherwise is hype. The best chance for someone to do it in our lifetime is probably Elon Musk -- and he's a long shot.
Something not discussed much is we currently do not have the technology to depart earth, land on Mars, and then again depart Mars. There is way too much fuel required for such a round trip.
Right now with our chemical rockets it is strictly a one way trip. The definition of a suicide mission. So people may talk and speculate, but I doubt anyone is going to seriously spend the kind of money needed in the hopes there might be qualified people who would actually accept the mission (ethical issues aside).
For those who would like to read more about the challenges this type of mission must solve before we can even leave the atmosphere I suggest you read Robert Braun's paper on the subject. Or at least read something lighter by wired which covers a wide range of challenges many of which we still haven't technically found proven solutions for.
EDIT: Undo specifically stated is there any real plan which means: "We have most of the technology to do this, and are anticipating doing this around 2018"
Since people don't seem to read the links...The honest answer is no, we don't have the technology (meaning "application of scientific knowledge for practical purposes") to do this. We think we understand the some of issues well enough to investigate building the hardware. Since no human has left earth orbit, survived in space and returned to earth, no one can even claim we understand all the technical hurdles. Even long term experiments in isolated biospheres in the Earth's gravity, atmosphere and sunlight have failed miserably.
In fact it wasn't until 2005 that we realized it was impossible to send a chemical rocket there and back. Yet ask the general public in 2004 and they would tell you we have the technology to do it--build a big rocket.
And this is an illustration of why it seems our progress to voyage into space has stalled. Not because it would just cost too much, but we do lack technology knowledge in many areas for such a trip.
As an example: NASA's popular solution barring a technology breakthrough is to use heavy lift rockets (which we don't have yet) to build the ship in space and haul all the mass out there first then launch from there. Do we know how to build a ship in space? Not really, but ISS has taught us a lot about what we don't know any we can start looking at tools to develop the technology for exo-construction. But we (humans in general) are way too early in the technological process to claim we can go to Mars and back by year XXXX.
EDIT2: As a recent follow-up on Feb. 2015, Gerard ’t Hooft, a Dutch Nobel laureate and ambassador for Mars One project, said he did not believe the mission could take off by 2024 as planned.
“It will take quite a bit longer and be quite a bit more expensive. When they first asked me to be involved I told them ‘you have to put a zero after everything’,” he said, implying that a launch date 100 years from now with a budget of tens of billions of dollars would be an achievable goal.