I have seen some interesting gamification elements developed by SweetRush - www.sweetrush.com
There's a white paper out from Towards Maturity (free thanks to the support of it's Ambassadors) which looks at the whole subject of Experiential learning including ramification. http://towardsmaturity.org/article/2013/06/05/online-experiential-L...
In this years Benchmark research, The New Learning Agenda: Talent, Technology, Change, (again free) (http://www.towardsmaturity.org/article/2013/05/07/towards-maturity-...) only 16% of over 540 organisation respondents use highly interactive methods such as games and simulations in their learning solutions - so not much out there from a best practice perspective to draw from. What the Benchmark also says is that L&D is not always designing for engagement so understanding what the learners want and need to do their job better will deliver better results. (http://www.towardsmaturity.org/static/learner/)
Hope this helps you - sorry can't recommend suppliers but can help with the best practice bit!!