Hi,
I'm not sure if this could really work, but I'd take a look into /etc/inputrc (or ~/.inputrc) and try to fiddle around with the settings. Usually the return-key is bound to accept-line. Maybe one could set that to something like (pseudocode)

kill-whole-line-to-register
system-command-with-register-content-as-arg
paste-system-command-output
accept-line
[download]

but I have never seen more than one command to be bound to a key neither the creation of own commands.
Of course this would be readline and could thus be used in a variety of other programms (like gnuplot)
Just my humble first guess...

Regards...	Stefan
you begin bashing the string with a +42 regexp of confusion