Michael Hutchinson implemented code analyzation quite some time ago, now that we've branched 2.6 we can add new features to master. I've added quick fixes & joined the two systems.
Quick fixes are like refactorings - they change code. But unlike most common refactorings they're much more fine grained and may add code. For example adding a property setter.
When the caret is on a position where a quick fix is available a little icon is showed indicating the fix. In conjunction with the AnalysisCore source code can be highlighted indicating a more pressuring fix which - for example removing code smells.
I've made a little demo of what is currently available in MonoDevelop master:
Link to quick fix demo.
I can need more suggestions for quick fixes & indicators. I'll try to add as many as possible - unfortunately this feature doesn't make it into 2.6. But it's available in master as well as some other exciting features.