A very simple addon (originally from DynamicBoxer) to generate random alphanumerical tokens at will to copy paste where needed.
Can also be a good "getting started with simple wow addons" sample code
Opensource multiboxing, dualboxing addon
Auction House DB, Database recording of the AH evolution for classic, offline queries
Gives you current stack and per full stack vendor sell price information as well as cheapest item in your bag (for when full) and more
Alignment grid, cursor coordinates, measuring tape made using the Pixel Perfect part of the MoLib library