Often we store documents in repository becouse we have something to do with them. In Keepmark you can mark some of documents as tasks, and add aditional description to them. It's the easiest way to move your work forward.
You can also create tasks not related with documents. Just create simple task, and add description to it. You can also pick a date when you should take care of given task.
You don't need 3rd party service providers to maintain your tasks list - you can do this with Keepmark and keep your data private.