The two tools that we use for email stationery design are Adobe Photoshop and Illustrator. Most of our designs are inspired by existing web sites so there is not much true graphic design required. We do a lot of manipulation of screen captures and focus on layout more than design.
As for creating branding solutions, this is more complex than people might think as there are so many facets. I know of Realtors that pay $ 7500.00 for a complete branding from the new headshot, a new logo, colors and fonts and a stationery package.
You can see a few examples of my branding projects in a blog post I wrote at http://themarketingguy.wordpress.com/2008/06/25/recent-business-card-designs/
Keep in mind that a Brand is intangible. It is the meaning or feelings you associate with a service, company or product. If ten people are asked to describe your business or product, you may get different descriptions, however, it is the similarities that are the brand.
A Brand is not a logo. A logo only identifies the brand; it is an entry point.
A Brand is not a product. Many people talk about managing their brand, but they really are managing their product. The brand is often the reason we buy the product.