I've never tied with squirrel fur strips; in fact, I've never noticed them in fly shops. I'll have to take a look for them. I like the flies you guys have posted with them.
Squirrel tail hairs are a little squirrelly to tie on in a clump sometimes, because they are so round and non-compressable. But, there are a few outstanding patterns that depend on them (think Bob Triggs' "Chum Baby"). After reading Roderick Haig-Brown's "Fisherman's Winter" about fishing in Patagonia, and before my first trip down, I tied a fly he describes (but doesn't give a recipe for) that relies on a squirrel tail wing. It was deadly in a great little Brook Trout stream in Mendoza.