Graphs

Bar Graph - Enter data to create a bar graph, then manipulate the graph's maximum and minimum values.
http://www.shodor.org/interactivate/activities/bargraph/index.html

Bar Graph Sorter - Sort colored shapes into a bar graph. Appropriate for elementary grades.
http://www.shodor.org/interactivate/activities/bargraph2/index.html

Circle Graph
http://www.shodor.org/interactivate/activities/piecharttool/index.html

Create a Graph - Enter data categories and the value of each category to create a circle graph. Similar to "Pie Chart" but the user can define the data set.
http://nces.ed.gov/nceskids/Graphing/

Interpreting Data - The site includes an excellent interactive tutorial about interpreting data.  A fact sheet and test are provided.
http://www.bbc.co.uk/schools/revisewise/maths/data/11_act.shtml

Let's Graph - Works in Netscape Only - The site explains a graph sample and provides opportunities to make adjustments to personalize the data.
http://math.rice.edu/~lanius/Lessons/graph.html

Pie Chart - Students view piecharts. Parameters: Number of sectors, size of sector as a percent.
http://www.shodor.org/interactivate/activities/piechart/index.html

Grids

Planet Hop - Students are asked to find the coordinates of the four planets on the grid and the find the equation of the line created.
http://www.bbc.co.uk/education/mathsfile/shockwave/games/planethop.html

What's the Point? - This activity provides a set of coordinates to identify on the graph.
http://www.funbrain.com/cgi-bin/co.cgi?A1=s&A2=2