Oh, how I love free things. Especially free pretty things. And I'm the kind of person who things Flash charts and graphs are pretty, so I present amCharts and PHP/SWF Charts. amCharts is a relative newcomer that creates attractive Flash pie and donut charts based on data you put in a text file in either XML or CSV formats (which makes exporting from Excel easy). It's very configurable, allowing you to specify colors, border, tilt (for a 3D effect), labels, fonts, backgrounds, and so on. amCharts' creators promise bar, column, and line charts this spring.

PHP/SWF Charts is sort of amCharts' big brother. It's been around awhile longer and features more than a dozen different chart types and nearly unlimited configurability. As the name implies, PHP/SWF Charts uses PHP to load data from dynamic sources, but it's not required--there's XML/SWF Charts that will load data from a regular XML file. With its advanced features comes more complexity, of course, and the learning curve is probably greater, but if you need, say, a stacked 3D column chart, it's the way to go.

As I mentioned, both charting tools are free, but not totally free. The free version of amCharts will put a small link to amCharts.com in the corner of your charts, and PHP/SWF Charts will direct users to its web site if they click on it. For a single-site license amCharts will cost you 45 Euros (about US$60) and PHP/SWF charts will cost you US$45. "Enterprise" licenses for unlimited sites cost 245 Euros (~US$322) or $550 respectively.

What does the 5 in Calc5 stand for? I have no idea. Rest assured, though, that this slick Ajax calculator does support most numbers, including those greater than five. At first blush there's not a lot to set Calc5 apart from the crowd. It works as advertised. But then you get into the advanced math and graphing functions, and that's where Calc5 really stands out. While it's distinctly lacking in documentation, the built-in samples will get you started. You can use unlimited variables, you can do derivations, you can find derivatives, and more, but most impressively you can make fast, attractive graphs, both 2D and 3D. The 2D graphs are very cool--smooth lines, and a Google Maps-like interface that lets you pan and zoom with the mouse. The 3D graphs aren't quite as cool--they lack the pan and zoom features--but still. 3D graphs will always be cool. The site automatically saves your previous calculations (via cookies), which is handy, but there's no built-in permalink system for sending calculations or graphs to your friends and colleagues. I can only assume this functionality is coming.

There are a couple undocumented features (well the whole app is undocumented, so take that how you will) I discovered that you might find useful, though:

1. Pressing Ctrl+Enter is equivalent to clicking the "OK" button. Very handy.
2. You can link to an equation by putting it after a pound sign following the URL. So if you wanted to help your friend solve, say, 2+2, you could point them to calc5.com/#2+2. Your friend will still have to click on the "OK" button (I hope this changes soon), but it works. First person to send me a Calc5 link for the Valenzetti Equation gets a free trip on Oceanic Airlines.

Calc5 is fairly powerful, especially with those graphing features, but it's clearly still very beta. Once they get some real documentation in there and some more convenience features, it could become indispensable. For now I'll probably stick to Google Calculator for the easy stuff, and Instacalc for the more complex stuff--unless I need to do some advanced graphing.

Blogger and web designer Vitaly Friedman has put together a very handy list of nifty tools for drawing diagrams, charts and flow-charts. He identifies about 20 resources spanning free software, commercial software, web-based tools, and tutorials that will help you make pretty graphs, charts, and diagrams. Of course, I'm most interested in the free stuff, but if you use Illustrator or Excel, or are looking for something a little more robust, the tutorials and commercial tools could prove invaluable.