Are there any ways to get additional arrowheads? I am using Powerpoint to create a football playbook and powerpoint would be perfect for my needs if I could add an "arrowhead" that was a flat, perpendicular line (it would look like an uppercase 'T').

I was hoping there might be an Add On with additional line styles and features or if I could create a WMF file could I somehow add that to the program? I've googled this problem with no luck so any help is greatly appreciated and will save me a ton of time and money I might otherwise dish out to a football playbook software company.