I frequently refer to these resources in my coaching and consulting work. If you have any questions about them, please contact me.
Lominger's Leadership Architect Sort Cards are a useful tool for defining the skills and capabilities possessed by an individual or required in a specific job or work environment. They're helpful in identifying untapped strengths as well as areas for improvement. They can also be used to understand where a person's capabilities and their responsibilities are aligned (and where they're not) and to determine whether a particular position or organization is likely to be a good fit for an individual.
An important note: Any productivity system can add to our stress and anxiety (and guilt!) if we force ourselves to conform to the system rather than adapt the system to fit our needs. I don't apply GTD techniques religiously (or even consistently), and that's just fine--it's still been very helpful.