I've read many threads on SitePoint about browser wars, and there is almost always a brief exchange of:
"I put 'FireFox ONLY!' on all my pages.'
"That's treating your users bad. It's their choice."
Well just to spark a bit of debate, I thought I'd let you know, GOOGLE DO THIS TOO!
For the people who will cry 'lies', here's a screenshot of my gmail: (might need to wait till attachment is approved -- someone please confirm this?)
I'm not supporting or criticizing this, just letting people know, when done respectfully it can really work.
Edit: Turns out Operas website does this too! (found this out by total coincidence in this thread.)