i'm currently using the random macro (thank you warcraftpets.com!) to summon a random companion, however i felt the need to take it one step further.
with just a couple extra lines of simple script, i edited my current random pet summon macro to activate whenever i mount or press it to dismount:
#showtooltipof course i still use the random summon macro for times when i can't mount up, but now i can have even more pet fun while continuing to be efficient in everyday activities! it's great to have a random non-combat pet out with me to make all those mundane and boring dailies more enjoyable. :D
/run CallCompanion("CRITTER", random(GetNumCompanions("CRITTER")))
/use Great Purple Elekk