When Snow Leopard first came out, I wrote about the new-and-improved Services feature, including what seemed to be a bug regarding which Services do and do not show up in the contextual menu. For example, try this experiment on your 10.6 machine. Select some text in TextEdit, then Control-click on the selection. In the contextual menu that appears, you should see three entries at the bottom of the menu: New Note With Selection, New Email With Selection, and Make New Sticky Note.
If you don’t see these entries, you’re experiencing the bug I discussed in the original article—which seems to be alive and well even in these days of 10.6.2. So how do you fix it? Fairly easily, thankfully. Open System Preferences, click on Keyboard, then click on the Keyboard Shortcuts tab. In the left-hand column, click on Services.
In the right-hand column, scroll down to the Messaging section, where you’ll see the two entries for New Note With Selection and New Email With Selection. Both will (most likely) have check marks next to their entries; go ahead and remove that check mark by clicking the box next to each item, then click again to put the check mark back. Simply toggling the Service off then on should be enough to get it working again. Repeat this process for the Make New Sticky Note entry in the Text section, then switch back to TextEdit.
Reactivate the contextual menu on your text selection, and you should see those three entries at the bottom of the list. You can try this trick with other entries in the list of Services—for handling tasks other than text selection, for instance—but not all of them will show up in the contextual menu—apparently that’s a design decision to prevent the contextual menu from getting too long. So as I wrote in the original piece, if you’re looking for a Service, make sure you look at the Services menu too, as it will contain entries that you won’t see in the contextual menu.
Personally, I find this behavior confusing, and wish OS X would just list all enabled Services in the contextual menu—I find it much easier to look there than to navigate up to the File -> Services menu any time I want to use a Service (that I haven’t assigned to a keyboard shortcut, that is).