Poll: Do you make use of externalid? If Yes, how do you keep the externalid from being overwritten by another app (integration, etc.) I've tried a few things, but wanted to know if there was a better way? I've tried monitoring what user role is attempting to change that field and restrict it to a role ... with hit 'n' miss results.

I tend not to use the native field for exactly this reason. The native field can get "crowded" if you have more than one integration looking at the same records, which I've found is almost always the case. Instead I create my own custom field specific to the integration I'm building and configure that with very limited access permissions (usually an integration-specific role). Then I bundle it up with my project, I can maintain control over its settings, and I don't have to worry about some other application overwriting it.

Thanks @erictgrubaugh I'm in agreement