Yes, the dreaded 'M' word.

You've got a workstation, source control and half a million lines of source code that you didn't write. The documentation was out of date the moment that it was approved and published. The original developers are LTAO, at the next project/startup/loony bin and not answering email.

What are you going to do?

{favourite editor} and Grep will get you started on your spelunking through the gnarling guts of the code base but what other tools should be in the maintenance engineers toolbox?

To start the ball-rolling; I don't think I could live without source-insight for C/C++ spelunking. (DISCLAIMER: I don't work for 'em).