With the addition of several new (and very cool) vanity pets in the most recent patch I feel like this thread deserves a bump. Switching vanity/buff pet powers to be a toggle that summons them at your location instead of being a ground targeted toggle power would allow them to be used with the "Pow_Exec_Toggle_On" command and make summoning them with a single button press much more convenient.
For example binding your W key to "+forward$$powexectoggleon pet: spiderling" would cause your W key to summon your spiderling vanity pet the first time you move forward after zoning and then function as normal while your pet is out. As it stands the above binding just activates the summoning cursor and requires an additional mouse click to complete the action. The only way to summon one with a single press would be by using "powexeclocation me pet: spiderling" which unfortunately would detoggle the power with the second press.