
There are many ways to limit the access to some areas to some people, and many possible applications, here are some of them to give you an idea.
Time attendance and other applications that are not destinated to physically forbid access but rather to manage people are stored under:
Virtual access to devices are stored under:
(2007 Aug) The Sea and Crystal Lounge nightclub (Glasgow/Scotland) is launching the hi-tech door-entry system in a bid to keep out underage drinkers and troublemakers (via Evening Times).
(2007 Jan) A football supporter has his finger scanned in the Netherlands. Ajax football club has set up a trial system to prevent banned supporters from entering the stadium. A computer stores the prints of barred fans and shows a red light if they try to enter.