I'd echo Mounir's advice. Unless you are in a situation where those 15 resources are significantly multitasking (in which case you have a more serious problem to resolve), Excel is a good place to start.
From there, the next step might be to look at creating a standalone resource pool for scheduling purposes using a tool like MS Project.
Only once you've exhausted the capabilities of those AND you have consistent resource management practices in place should you consider any type of advanced PM/PPM solution.
TaskQue is a very good cloud based application which helps in managing all the tasks in a swift manner while allowing the assignee to add a comment about task progress, on the other hand, you can check progress summary of projects and can reopen tasks with added comments about what improvements are required in delivered work.
You would just have to pay $5 per user which I believe is not a big deal for aligning all the work and getting control of it remotely. Saving Changes...
