Mount/Pet Mods
Coconuts ,
Coconuts adds a button to your interface that smartly decides a random mount for you. If you're in Outland and have a flying mount, it will pick it! Also lets you dismount. Easy switching to a slower mount or to a ground mount if you need to. To pick your next slowest mount, hold down (default) Shift and click the button. To pick your ground mount while in an area which allows flying and you have a flying mount, hold down (default) Alt. To dismount while on a flying mount, hold down Shift, Alt, or Ctrl. To use Holly on your mount if you have any, while mounted hold down (default) Ctrl. The button action can also be bound to a key using WoW's key interface or by entering /kb into the chat then clicking the button and pressing the key you want bound to it. Coconut also understands travel forms, including flying and aquatic!
Curse
Collectinator
Provides methods for determining which mini-pets and mounts you are missing.
Curse, WoWInterface
Collect Me
Collect Me keeps track of your companions (minipets) and mounts in the game and can show you your missing pets and mounts with additional information where to get them. It also can summon companions randomly with a priority list.
Curse
GoGoMount
One-key mounting solution, useful whether you have just one mount or several.
Supports all mounts currently in game, sensibly chooses/randomizes between what you have.
Bind a key and hit it to mount/unmount or shapeshift/deshift, or use '/click GoGoButton' in a macro.
Curse
GupPet
GupPet is an add-on that gives an extension for mounting and calling critters. By a single click it mounts a ground, swimming or fly mount depending on the players location. Because most players have plenty of mounts and companions, and you probably like more than one, the add-on can randomly select mounts/companions depending on the selections in the option menu.
Curse
MountRandomMount
Randomly cast a mount from a defined list using land mounts in nonflyable areas and flying in flyable areas.
WoWInterface
PetShop
PetShop will track every Companion your toons knows and add lines to the GameTooltip to show you which toons currently have that Companion and which toons are missing it. PetShop currently works with every tooltip I can think of, Mailbox, Backpack, Auction House, Trade Window, Loot Window, Chat Links and the Companion Frame.
Curse
sCompanions
Creates slash commands for flying mounts, ground mounts, and pets. These can then be placed into macros.
/scompanions ground,
/scompanions air,
/scompanions pet;
these will select a mount or pet at random.
WoWInterface
Squire2
Squire creates a macro named "Squire". You can use this macro as any other macro. You would probably put it into an action bar. Squire updates its macro when need (entering/leaving buildings, combat or instances, etc.). Features: properly handle Northrend (non-flyable zones and the Cold Weather Flying skill), support all mounts listed on wowhead.com, select a random flying and ground mount every time the macro is updated, use macro conditionals to allow responsive behavior.
Curse
Yay Mounts
Provides a one button solution for mounting; allowing you to ground or flying mount, dismount, exit vehicles and shapeshift as a druid or shaman with one button. It includes a GUI for selecting which mounts you want to use. Yay Mounts is most useful for players with a large number of mounts, but only a handful that they actually want to use regularly. Players with very few mounts can still find it useful.
The GUI can be accessed by typing "/ym" or from the Blizzard options window. You can set the keybinding from the /ym GUI options or the Blizzard keybinding menu.
You can also make a macro by using "/click YayMountsButton".
WoWInterface, Curse