18. A tangible medium comprising computer-executable instructions for conveying theme elements to a plurality of documents; comprising: associating a theme object with a first document authored by a spreadsheet application; wherein the first document is associated with a spreadsheet file format that includes modular parts that are associated together; wherein the theme object is a modular part that is associated with the spreadsheet file format; wherein the theme object is defined using a markup language; wherein the definition of the theme object is maintained separately from other objects that define the spreadsheet file and that are each maintained separately; and wherein a schema defines and enforces rules for displaying the theme object; associating the theme object with a second document authored by a word processing application; wherein the second document is associated with a word processing file format that includes modular parts that are associated together; wherein the theme object is a modular part that is associated with the word processing file format; and associating the theme object with a third document authored by a slide presentation application; wherein the second document is associated with a slide presentation file format that includes modular parts that are associated together; wherein the theme object is a modular part that is associated with the slide presentation file format; wherein associating the theme object with the first document, the second document, and the third document provides a common appearance for the first document and the second document and the third document.
18. A tangible medium comprising computer-executable instructions for conveying theme elements to a plurality of documents; comprising: associating a theme object with a first document authored by a spreadsheet application; wherein the first document is associated with a spreadsheet file format that includes modular parts that are associated together; wherein the theme object is a modular part that is associated with the spreadsheet file format; wherein the theme object is defined using a markup language; wherein the definition of the theme object is maintained separately from other objects that define the spreadsheet file and that are each maintained separately; and wherein a schema defines and enforces rules for displaying the theme object; associating the theme object with a second document authored by a word processing application; wherein the second document is associated with a word processing file format that includes modular parts that are associated together; wherein the theme object is a modular part that is associated with the word processing file format; and associating the theme object with a third document authored by a slide presentation application; wherein the second document is associated with a slide presentation file format that includes modular parts that are associated together; wherein the theme object is a modular part that is associated with the slide presentation file format; wherein associating the theme object with the first document, the second document, and the third document provides a common appearance for the first document and the second document and the third document. 19. The tangible medium of claim 18 the instructions further comprising storing the first, second and third documents in a markup language.