Kutools for Excel - A handy Microsoft Excel add-ins collection to free you from time-consuming operations.
Invantive Control for Excel - Invantive Control enables you to make decisions with Microsoft Excel and yet remain fully compliant...
Devart Excel Add-ins - Devart Excel Add-ins allow you to connect Microsoft Excel to live database and cloud data and work with them as with usual Excel spreadsheets.
Yasai - YASAI is an open-source Monte Carlo simulation add-in for Microsoft Excel
CData Excel Add-Ins - Excel Add-In for mass imports / exports / updates, data cleansing & de-duplication and data analysis.
@RISK - @RISK is the world's most widely used risk analysis tool.