One of the powerful ways to leverage SharePoint and BPOS's SharePoint Online Standards is with Content Types.  SharePoint Content Types allow you to define a standard set of metadata about individual pieces of content.  In a given Document Library you can have many, many content types.  For example, you might have a library called Customer Documents and within that library you might have three content types - "Contracts"  "Project Documents" and "Time Sheets".  In the Contracts Content Type you would have a set of defined columns. Some of these columsn would be custom - such as "Customer Name" but others you'd pull directly from SharePoint Core Columns such as those having to do with mailing addresses.  As a part of every SharePoint site you should create the content types that you will use with your document libraries. This will allow you to enhance search, workflow, usability, findability and have create views that do the heavy lifting of manual foldering.

In BPOS to get started with content tpes you need to first go and ahead and see what Microsoft has built for you -  to do this go to Site Actions > Site Settings > Site Content Types.

Next - Click on any Content Type - as an example I have created "Proposals" - you probably will not see that option so choose Document. 

Explore the columns that make up the Content Type. Then add a new or add from existing. The next screen shot adds a new column.

Adding a new column is easy - I like to use Calculated Columns from time to time. I am going to use a Calculated Column because I want the "Customer" to display as an aggregate or combination of multiple columns.  This makes for easy viewing - I can combine multiple values into a single text string value.

Here's where I add my formula. The result of this formula will space with spaces "Company Phone Phone" in the Customer field throughout my list.

This is a nice summary - but to work with columns and Content Types you need practice.  Try making a view of your own with your BPOS SharePoint Online Standard sites.

More Reading:

http://msdn.microsoft.com/en-us/library/ms472236.aspx