I admit that every so often the freakish superintelligence of the GNU versions of programs has its appeal. Consider, say, units :

You have: 7 feet + 2.5 inch
You want: mm
        * 2197.1
        / 0.00045514542

GNU date is another good one:

; date -d 'last sunday'
Sun Apr 13 00:00:00 EDT 2008

Or even better:

; date -d 'last saturday -1 week'
Sat Apr  5 00:00:00 EDT 2008

(Judging from the manpage, BSD date may also have some freaky superintelligent date math stuff, and judging from some experimentation, GNU date is not all that superintelligent, or at least not that well documented, since I couldn't see an obvious way to do something like 'the third Saturday in January 2008'. As an aside, the GNU date documentation perfectly illustrates the downfall of the GNU's (text)info documentation format.)

Also, I will admit that sometimes GNU is plain right about things. For instance, I'm pretty convinced that the -h option to df , du , and ls just is easier for people to read; I find myself usually using it unless I am going to feed the output to something else.