KM4OLT - Mike's Ham Home
Digital Mobile Radio - an open digtal mobile radio standard. Some hams prever DMR over D-Star for the simple fact it's open. The radios tend to cheaper as well. The goal was low complexity and being able to interoperate across bands.
DMR versus dPMR comparison - Wikipedia entry on DMR
DMR versus dPMR comparison - Part 1 of a series from Tait Communications.
Amateur Radio Guide to DMR - Looks to be a good reference on DMR and understanding it better.
What is DMR? | Tait Radio Academy - a good video on the introduction to DMR.