Percents
Virtual Manipulative: Percentages
Interactive tool where you fill in any two of the three 'boxes' (whole, part, and percent) and it will calculate the missing part and show the result visually in two ways. 
Comparing Decimals, Fractions and Percents
Comparing Decimals and Percents
Fraction converter
 
Percentage Estimation - try to estimate what percentage of the bar has been shaded.
Pie Test - Estimate the size of the sector of the pie chart which has been shaded yellow..
Penguin Waiter-Calculate Tip
Percentages – Discover relationships between fractions, percents, and decimals.