Chart Chooser from Juice Labs offers a wide variety of pre-made charts that you can download and use for free. These include: Pie chart, Bullet bar chart, line chart, bubble chart, column chart, and many more. You can use the search filter to look for charts for both PowerPoint and Excel. You can refine your search by targeting charts in a specific category from the 6 categories featured there (e.g comparison, distribution, composition, trend, relationship, and table). Once you find the chart you want to use, hover your mouse over it and click on download and there you go.