Is there a scale drawing of SMD package sizes as a design aid? This could be useful in schematic/layout stages of a project in when deciding to trade off size vs. cost.
TI has a nice pdf chart for their ic packages, at actual size. Organized by pin count and package type. This is Texas Instruments centered, but the information translates well between manufacturers.
In my experience, a printer is the most useful design aid / sanity check. For example, I use Eagle to design my PCBs, and there are reference packages available for a very large range of devices. Simply printing out the design 1:1 helps a lot. It can also help you see things like "Those parts look like they would be hard to solder/probe" and "These parts are too close/far away". It's also cheap and fast. Some manufacturers will put 1:1 footprint drawings in datasheets as well, and you can use those for reference.
As for a specific design aid, I also have the SparkFun Reference Board, which helps you see what holes, text, and common packages look like on a footprint. I find it useful at times, especially when I'm trying to figure out readability of text.
I know this is an old post but to add to the knowledge base (for those who google it around like me) I found the following link for SMD standard size chart
Hope this helps! :)