iWork apps only allow hyperlinks to web pages, to create email messages, and to bookmarked pages in your iWork document. However, I find it useful to have links to other files in the iWork document, as it saves digging around the file system. I normally create links by selecting the file in the Finder then going to Services » TextEdit » New Window Containing Selection. This opens a TextEdit window with a link to the file, which I can then copy into any Cocoa based document. iWork apps, however, only paste this link as text.

To overcome this, I type in a line of text in the document (or in a comment) that specifies some combination of Spotlight type, attribute, and search text. I can then highlight this text and use a keyboard shortcut for the Spotlight Services menu item to bring up a Finder window containing matching items. This search can be very precise if required, and has the additional benefit that if the files are moved, they can still be found -- a traditional link would break if you moved the source file.

First set up a keyboard shortcut for Services » Spotlight. Go to System Preferences » Keyboard & Mouse » Keyboard Shortcuts, and add a keyboard shortcut as follows:

• Application: All Applications
• Menu Title: Spotlight
• Keyboard Shortcut: Shift-Command-F

Now you need to set up your Spotlight search strings.

Here are some examples of Spotlight tags I might use. For each of these, I highlight the line of text, then press Shift-Command-F to run a Spotlight search using the selected operators:

• Search for folders named "sites:" kind:folder name:sites
• Search for Pages' documents with either "Spotlight" in their name or contents: filename:pages spotlight
• Search for Numbers' documents with "spotlight" in their name: filename:numbers name:spotlight
• [10.5 only] Search for Keynote documents with the phrase "step one" in them: filename:key "step one"

This Apple document covers some of the ways to specify search criteria in 10.5, and includes a few useful examples, and this one shows you exactly what types of applications you can specify with the kind: modifier. There are lots of other attributes you can specify; see this hint for a long list.

[robg adds: I tried forcing Pages to create local links by specifying a file:/// URL, but Pages inserts an http:// at the front, so that didn't work. You could work around this by creating a local HTML page that links to the file you'd like to access, but that seems like a lot of work.]