How do I customize the top banner, so that it displays my company's org, rather than the standard Salesforce.com logo?
The logo that displays in the top left corner is defined by the application that you are currently running. Salesforce apps are selected using the drop-down in the top-right corner. In the image below, I'm running the "Ideas" app, which uses the Salesforce.com Service Cloud logo.
TRIVIA: The default logo is updated several times a year, with each seasonal Salesforce.com upgrade. Salesforce.com usually comes up with two or three different logo ideas, and offers Customers a chance to vote for their favorite logos on the Idea Exchange. The logo that wins the most votes is used for the next release.
If you want your own custom logo, then you'll need to build your own "custom app". That's not nearly as difficult as it might sound. In Salesforce.com, an App is simply a group of Tabs. The "Sales Cloud" app includes tabs like Account, Contact, Lead, Opportunity, etc. You can create a custom app that uses these same Tabs, but features your company logo. Here's how:
1.) Using image editing software, modify your company logo so that it is less than 300 pixels wide and 55 pixels in height. The image must be a GIF or JPEG format, and less than 20 KB in size. Save this image to the Documents tab. Be sure to mark the image as an "Externally Available Image" when you upload it to the Documents library (see below):
Follow the App Wizard prompts to give the App a name, add your logo, and select the tabs that you want to be visible when users run this app.
That's all there is to it!
TIPS AND TRICKS:
Use a logo with a transparent background, unlike my sample above. If you use a logo with a colored background, you'll spend a lot of time tweaking the color scheme of your tabs so that they don't clash with the banner. The cyan background in my sample doesn't blend very well with the default green of the home tab logo ... blech!
During the photo editing stage, trim your logo so that it is exactly 300 x 55 pixels -- even if that means adding a filler space around the edges. If your logo doens't match these dimmensions exactly, Salesforce will resize the image to fit, but not always. You may find that your logo is distorted on some screen transitions, or that it displays outside the banner borders.
Each App that you build can have it's own logo. The number of Apps that you can make (and/or upload from the AppExchange) depends on what type of licenses you have:
The custom app that you build (just so that you can display your own company logo) does count against the number of Apps you can download and run from the AppExchange -- so keep that in mind!
Pretty quick, pretty simple!