Are there any utilities out there which can draw pictures of the merge history of a subversion repo - we always commit merges with a (fairly) consistent log message, and it would be handy to be able to automatically extract this info into a single picture that shows what branches occurred when, and what the state of merges is.
I'm just interested in an informational tool, not something to help with actually performing merges.
TortoiseSVN can show revision graph - visual representation of branching\merging history.
You can have a look at some of the visualisation techniques used here, for inspiration if you are developing your own system, some nice ideas.
RaphaelJS Github Vis Code Swarm
Probably you know some of this already!
I use SmartSVN for this; I has a very quick and easy to use revision graph, which can show svm:mergeinfo as colour coded links and arrows between branches. It's pretty hard to beat when looking at a good-size source tree