Can You Help Identify the Source of My Coolant Leak?

[shertex]

Found my slowly-leaking coolant (about 1/2" in expansion tank every 1,000 miles). It's pooling on some sort of lip directly beneath the engine side of the upper radiator hose (see pic). However, it doesn't seem to be leaking from the hose itself (although I'm not positive about that). The coolant seems to be somewhat broadly dispersed, extending even to directly beneath the fuel filter.

Any ideas? What are the possibilities?

Thanks.