Just be careful about Microsoft's Patent US6748582B1; it doesn't expire for another few months. ;)
From the patent (edited down a bit):
> According to various example implementations of the invention, a task list facilitates code development by assisting developers in keeping track of and managing a variety of tasks, such as errors to be corrected, opportunities for optimization, and other user-defined tasks. As the developer edits source code, warnings and coding errors are detected and inserted as tasks in a task list. The developer can also embed keywords known as comment tokens in the code. These comment tokens are detected and used to define tasks.
> [...]
> Tasks can also be identified using tokens or keywords. These tokens or keywords typically preface comment lines in the code and may include predefined labels such as, for example, “UNDONE,” “TODO,” or “HACK,” as well as labels that are defined by the individual developer. If the source code has no syntax errors, the parser [...] determines whether any of the keywords are present in the source code[.] If so, [it] extracts the comment from the source code and uses the tag to determine the priority of the task. The task is then inserted in the task list[.] For example, if the source code contains the comment, “/TODO: Need to add copyright text/”, the parser [...] adds the task “TODO: Need to add copyright text” to the task list with a priority rating assigned to the “TODO” tag. [1]
[1] http://patents.google.com/patent/US6748582B1/en