Is Playing games as in Lumosity.com really effective. Can that boost my attention span, concentration skills? How else can it benefit me?
I have tracked my own progress daily on a bunch of different games (jigzone, crosswords, etc.)
Not to mention my daily SO "training" ;)
Hmm... It's certainly got a lot more going for it than normal "Improve-you-Brain!" promises - they've embraced science as a marketing tool http://www.lumosity.com/documents/the_science_behind_lumosity.pdf talks about control groups and p values and that's very nice...
Your best bet for information is Nature - who we can consider to be pretty authoritative on most things. In http://www.nature.com/nature/journal/v465/n7299/full/nature09042.html?lang=en they go into the problem of 'brain training' in detail (not lumosity in particular, but all similar sites) and conclude.
Or to put it another way - people get better at playing the games, but this doesn't make any different to the rest of their life.