Is it possible to define template files for the context-menu? I often have to generate files (for example letters), which should have a certain content at the beginning (e.g. letter head,...). In Many Linux-Distributions there is a folder called ~/Templates - Every file in this folder appears in the context-menu/"File new" and is copied to the folder after selecting this entry.

Is something like this also possible in MacOSX 10.6.8?
There is no equivalent user or system wide feature in Mac OS X 10.6.

However, many applications support Stationery Pad documents. These are documents marked as read only and when opened create a new untitled document using the original document's content.

The Stationery Pad option is available in the Finder > Get Info panel:



tuts+ has a tutorial explaining how Stationery Pads can be created and used.