Being able to list all files within the current directory tree that have changed within the last n minutes is really handy. It can often help you locate files created by unfamiliar software (most especially log files, but many other things too).
GNU find
If you're on a box that has a real GNU find on it, these will work:
find -mmin -60 # find files modified less than 60 minutes ago
find -mtime -1 # find files modified less than 1 day ago
find -mtime +5 # find files modified more than 5 days ago
# (prefix '-' means 'less than'; prefix '+' means 'more than'; no prefix means 'exactly this many')
find -newer ./ref # find files that are newer than the specified file
Perl
This solution is nice because it's more cross-platform than the other solutions. (on Windows, install StrawberryPerl)
# everywhere
find2perl -mtime -1 -type f -print | perl
# Un*x
perl -MFile::Find -le 'find sub {print $File::Find::name if -f && -M $_ < 60/1440 }, "."'
# Windows
perl -MFile::Find -le "find sub {print $File::Find::name if -f && -M $_ < 60/1440 }, '.'"
The '60' there is the maximum age in minutes.