These don't have a particularly large number of tags, but I think an implication of this sort might be useful a la the turntable decision:
cellphone -> phone (636 posts)
corded_phone -> phone (89 posts)
cordless_phone -> phone (24 posts)
phone_booth -> phone (12 posts)
iphone -> cellphone -> phone (10 posts)
payphone -> phone (8 posts)
string_phone -> phone (6 posts) (maybe)
The last few have next to nothing, but I could see all but the last easily growing (there have to be at least several instances untagged uploaded already). The implications would allow for easy searching of a more general concept without convoluted queries, and encourage more descriptive tagging without increasing fragmentation.
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