important feature for head/tail

A) behind the scenes, if these programs arent already almost the same
source, they should be

B) MORE IMPORTANTLY: i think its very useful to have the following
features in either head or tail:

instead of just tail -n10, which takes the last 10 lines, there should
be a way of doing all lines from line 10 to the end.

C) i think this really calls for a new application to be created from
these 2. Some of its features wrt to cropping the file:

first N lines
last N lines
last lines from line N
lines from line N to line M

and then give it the best other features from head and tail. 

EXAMPLE: since its all in 1 file, and now all the features support
"follow" you can:

take lines 20-30 from a file and then -follow it into another file
take all lines after line 5 and then -follow it into that file

very very useful....