Display Peter's keyboard pattern
Perl, 63 chars
say for&quot;1234567890JIHGFEDCBAKLMNOPQRST!?,.ZYXWVU&quot;=~/(?=(...))/g

This solution uses the say function (available since Perl 5.10.0 with the -E switch, or with use 5.010).  Without it, the best I can do is 67 chars (and an extra newline at the end of the output):
print&quot;1234567890JIHGFEDCBAKLMNOPQRST!?,.ZYXWVU&quot;=~/(?=(...))/g,$,=$/


Earlier 65-char solution:
s//1234567890JIHGFEDCBAKLMNOPQRST!?,.ZYXWVU/;s!(?=(...))!say$1!eg

Replacing say$1 with print$1.$/ lets the code run on older perls, at the cost of 5 extra characters.