Whether using iPhone Apper or OpenURL, just use the tel prefix and your phone number, e.g. tel:212-555-1212.
Update: By reader request, here's my dreadful icon.
Update 2: TUAW reader orijinal offers a really good point: the iPhone Apper page publishes "recently built apps", complete with Call Home instances that reveal your phone numbers in the URL. You may just want to use Open URL instead.