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
To sort by time:
find -mtime -1 | xargs -d '\n' -- ls -d -lrtF --color

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
find2perl -eval "(-M) < 60/1440" -type f -print | perl
The '60' there is the maximum age in minutes.