Reddit reviews Now You See It: Simple Visualization Techniques for Quantitative Analysis

Tools

Protovis (JS)

Axis (Flex)

28 Rich Data Visualization Tools


Blogs

Flowing Data

Infosthetics

Information is Beautiful

Visual Complexity

Cool Infographics

Infographics Showcase

Data Pointed

http://www.datavisualisation.co.uk/


Books

The Wall Street Journal Guide to Information Graphics

Now You See It: Simple Visualization Techniques for Quantitative Analysis

Beautiful Visualization: Looking at Data through the Eyes of Experts

This is a fairly useful review that I believe is available via google scholar for free: Wainer, H., & Thissen, D. (1981). Graphical data analysis. Annual review of psychology, 32, 191–241.

Tufte is useful for a historical overview and for inspiration, but he has a particular style that doesn't necessarily match up with the way that you or your audience think.

Hadley Wickham developed ggplot2 and his site is a good place to start browsing for guides to using it.

There's a pretty good o'reilly book on visualization as well, and Stephen Few's book does a really good job of enumerating the various ways you can express trends in data.

Excel is a program/tool that should service our sense of design and aesthetics; that is, we shouldn't constrict ourselves to it. Here are my recommendations on learning how to better graph information:

• Tufte is routinely recommended, and I find that he provides comprehensive, practical advice
  
• Another book recommendation but by Few
  
  If you were to post how your graphs currently look along with the data (scrubbed, of course), I'd give a crack at showing you what I'd do.

Stephen Few has some pretty decent, up-to-date books that make healthy reference to the past half-century's well-known sources such as Tufte, Bertin and others. It uses well-made examples produced with fairly modern tools.

I have enjoyed Show Me the Numbers and Now You See It and would say they are worth the read.

Read some work by Stephen Few and Edward Tufte on info viz. A lot of pointers and design claims/tips to be found there.

http://www.amazon.com/Now-You-See-Visualization-Quantitative/dp/0970601980

Aside from Tufte, you might find Cleveland's Visualizing Data worthwhile. I'm reading Stephen Few's Now You See It: Simple Visualization Techniques for Quantitative Analysis now.

Also, try following some related blogs, like Nathan Yau's Flowing Data or Kaiser Fung's Junk Charts. You can get a sense of some appropriate and/or inappropriate ways of visualizing data from these.

Finally, once you get more familiar, get something like Murrell's R Graphics. This will help you understand the basics of the base R graphics capabilities so you can make what you want, exactly how you want. ggplot2 is awesome, too, but understanding the basics is really helpful. Hope that helps.