A while ago I hooked up Haibo's ILReader to make a rustic Debugger Visualizer for DynamicMethod (Lightweight Code Generation). Haibo did the hard work and made it very interresting tool for debugging those strange .net citizens.
I'm a big fan of custom debugger visualizers. Not only they are very useful but they also very well documented and easily testable! There are already many implementations of those for datasets, xml, etc... but usually it worth investing a little time to build your own customized visualizers.
For example, if your data organized as a tree, you might be continuously drilling down this tree. You could consider a visializer that would render the tree to a certain depth. This will save you a *lot* of "expand node" time.