QuickChart - QuickChart is easy to use and open-source open API that makes it easy to generate chart images.
Kutools for Excel - A handy Microsoft Excel add-ins collection to free you from time-consuming operations.
Google Charts - Interactive charts for browsers and mobile devices.
Excel Dashboard School - Free Excel add-ins and tools on Excel Dashboard School. Boost your work productivity and save your time! No trials, 100% power!
Image Charts - No more pain rendering charts server-side.
KPI Dashboard in Excel - Professional Management KPI Dashboard. Includes trend charts, past year/target comparisons, monthly & cumulative analysis in performance dashboard.