Is there a tool that can be used to prohibit internet access for all applications except selected ones (on Mac OS X)?
"Little snitch" can't be the answer, as it doesn't provide a simple "deny all / allow some" rule.
Reason for the question: When tethering / connecting via iPhone's personal hotspot to the internet, Mac OS X will allow all applications to connect. Each app that needs to update or sync will do it and consume your mobile data quota (e.g. 1GB/month) very quickly.