EditPad Lite has a nice feature (CTRL-E, CTRL-I) which inserts a time stamp e.g. \"2008-09-11 10:34:53\" into your code.
For a unix timestamp:
:r! date +\%s
You can also map this command to a key (for example F12) in VIM if you use it a lot:
Put this in your .vimrc:
map :r! date +\%s