$ export HOSTFILE=~/hostnames
$ cat $HOSTFILE
example.com
me.homelinux.org
http://ftp.isp.com
$ ssh
example.com http://ftp.isp.com me.homelinux.org
$ ssh e
$ ssh example.com

But the lack of the ability to do something like
Host foo-%1
HostName foo-%1.bar.baz.bam
does make me sad.

#!/bin/bash
shopt -s extglob
isint(){
case $1 in
?([-+])+([0-9]) )
return 0;;
*) return 1;;
esac
}

if [[ -d ~/.ssh ]]; then

# Touch files we expect to exist
if [[ ! -e ~/.ssh/config ]]; then touch ~/.ssh/config; fi
if [[ ! -e ~/.ssh/known_hosts ]]; then touch ~/.ssh/known_hosts; fi

# Parse ~/.ssh/known_hosts and ~/.ssh/config to find hosts
for x in `sed -e ’s/[, ].*//’ ~/.ssh/known_hosts; awk ‘/^Host [^*?]+$/{print $2}’ ~/.ssh/config`; do

# Don’t override commands
type “${x}” > /dev/null 2>&1 && continue

# Remove the domainname
y=${x%%.*}
# you don’t want IP addresses for aliases, trust me.
isint $y && continue

# If it’s a short-name, move on
#z=${x##*.}
#[[ "${z}" == 'edu' || "${z}" == 'com' || "${z}" == 'net' ]] || continue
# So the above is commented out because you’d be surprised at how much you rely on your search path
# You should pipe the output of this script to sort and your fqdn’s will override your shorts.
echo alias “${x}”=”ssh $x”

if [[ "$y" != "$x" ]]; then
if ! type $y > /dev/null 2>&1; then
echo alias $y=”ssh $x”
fi
fi
done
fi

$ cat ~/.ssh/config
Host shortname
HostName some.really.long.hostname
User username_that_i_never_remember
$ ssh shortname # == ssh username_that_i_never_remember@some.really.long.hostname

Works regardless of your shell, and scp/sftp recognize the shortnames as well.