Taken from : http://www.macnn.com/reviews/omnigraphsketcher-for-ipad.html
OmniGraphSketcher for iPad
April 28th, 2011 Create and enhance graphical drawings, such as line art or bar charts
OmniGraphSketcher (OmniGS) lets you create and enhance graphical drawings, such as line art or bar charts on your iPad. You customize almost every part of the graph, including background color, line width, size, font, style, and text color. The only missing piece is that you cannot make pie charts.
OmniGraphSketcher (version 1.4) for the iPad is an application to create and enhance graphical drawings, such as line art or bar charts. It can be used to create charts from scratch, or to enhance existing charts created by other applications.
OmniGraphSketcher shows up as OmniGS on the iPad's home screen. While it is easy to use, it takes some practice to take advantage of all of its features. I created a table in a spreadsheet, copied the numerical data, and pasted it into OmniGS. Boom–I had a line graph, as shown below.
Simple Line Graph
I customized the graph and added a shaded area, some text, and changed how the data points were displayed. I added a background color, and I had this beautiful graph, as shown below.
Colored Line Graph
OmniGS lets you customize almost every part of the graph. When drawing a line chart, the data points can be connected either with line segments or Bezier curves. The data can be displayed as line, curve or bar charts, but not pie charts. You can set the color and width of the lines or bars, plus each data point can be displayed in many ways.
When creating a graph, you can import numerical data from another program via copy and paste, enter your own data points, or just draw freestyle lines or curves. Once you have a graph, you can edit the data points by tapping and moving them. When you are drag the data point around, OmniGS displays a small window that shows you exactly what the value of the current point. OmniGS also "snaps" to whole numbers, which makes it easy to enter those values. However, I could not find a way to manually edit the numeric data for exact values. When I drag a data point, OGS shows me the value as I drag, but it changes from 12.6834 to 12.69 to 12.6965 the smallest movement that I can make. If I want the value to be 12.691, there's no way that I can set that in OGS, so precision is a problem.
Once you have created the basic structure of your graph, you can use OmniGS’ array of tools to enhance it. The easiest thing to do is to add text labels. Just tap on a point in the graph, and a text label appears, along with the iPad keyboard. When you have entered the text, put away the keyboard and tap on the Inspector (i) menu item in the upper left corner. From that dialog you can customize the size, font, style, and color of the text.
Sample Bar Chart from The Omni Group
You can use the Inspector menu to customize any element of your graph. You can tap a point, line, label, or the axes to select it, then bring up the inspector to customize it. If you have nothing selected, the inspector lets you customize the look of the entire graph, and set things like the background color.
Inspector with Line Graph
OmniGS supports sharing your documents between your Mac and your iPad using either an iDisk or any WebDAV server to which your Mac and iPad have access. You can also sync files using iTunes.
I ran into a couple of problems with OmniGS. In the example graph above, I couldn't find a way to adjust where the text in the shaded area appeared, and OmniGS placed it too high for my taste. I ended up inserting three blank lines at the start of my text to move it down. For a program as flexible as OmniGS, this was a surprising lack.
Also, when sweeping out an area to shade, it is way too easy to change the underlying data in the graph. This caused me problems a couple of times. Fortunately, OmniGS has an Undo button, and every time I tapped, undo worked perfectly.
If you have a need for creating or annotating graphical presentations on your iPad, then I haven't seen anything better than OmniGraphSketcher. You can purchase OmniGraphSketcher through the iTunes store for $14.99.
Edited by Ilene Hoffman, Reviews Editor
-Easy to annotate.
-Easy to share your charts with other programs.
-Too easy to change the underlying data when enhancing a chart.
-Little control over where the text in a shaded area appears.
-Hard to be precise.