Old question is missing an up-to-date answer: Meanwhile, the solution is built-in to Android and called "Quick Settings".
- Go to Settings › Notifications › Quick Settings
- Tap the entry to chose/arrange tiles
- if "WiFi Hotspot" isn't shown on a tile:
- tap the + symbol
- scroll to the end of the list
- tap the corresponding entry to add (WiFi-Hostpot)
- optionally: move the tile where you like to have it
Now, toggling the hotspot is as simple as
- pull-down the notification bar from the right corner (this should immediately show Quick Settings)
- if Quick Settings aren't shown (but your notification area is), tap the top-right corner to switch over
- tap the hostpot tile
Some ROMs (such as CyanogenMod) even allow you to have the very same stuff "synced" to quick toggles placed on top of the notification area, for even easier access.