The Google Chart API lets you dynamically generate charts. Looks nice, and highgly configurable with colors, label, sizes, ... and there are many chart types: 1. Line charts 2. Bar charts 3. Pie charts 4. Venn diagrams 5. Scatter plots
API stands for: Application Programming Interface And for you other question, look at Google APIs Terms Of Service
Good news: - Usage Policy Extended: "There's no limit to the number of calls per day you can make to the Google Chart API." - New Chart Types: Sparklines, Radar charts, Maps