It isn't the most needed add-on of all time, and I initially created this for myself but I thought that others might find it to be useful too so it's now available on AMO.
Stylish Tools provides quicker access to the following Stylish features.
1. Write New Style
Access through the toolbar button or through Ctrl + Alt + U
2. Manage Styles
This allows you to manage your userstyles in a tab and not through Add-ons Manager > Stylish. The difference is that It loads much quicker.
Access through the toolbar button or through Ctrl + Alt + M
In Thunderbird, access is only available through the toolbar button.
3.Write style for... (this URL, etc)
Access through the toolbar button.



Compatible with the following
Firefox 20.0 - 23.0a1
SeaMonkey 2.0 (probably works with others but haven't tested)
Thunderbird 17.0 - 23.0a1
Stylish Tools on AMO.