Linux:
*) mono project should be installed together with the mono-tools and monodoc 
package. The binaries monodoc, monodocer and monodoc2html should be available 
then.

*) the compiler needs to know that he should generate the xml  file out of 
the /// tags like <summary> ... </summary>.
This can be achived with the additional option -doc:FILENAME when calling the 
gmcs (mcs for .NET 1.0) compiler in the console or by selecting "Generate XML 
Documentation" in the monodevelop IDE in the ProjectProperties.

*) Now a XML file should be present in the build directory (if no path was 
specified). We can now generate a documentation which should be readable with 
monodoc. This documentation is stored in some new xml files.
To generate it use:
monodocer -assembly:NameOfTheAssemblyFile.exe -importslashdoc:NameOfTheGeneratedXMLFILE.XML 
-name:NameOfTheProject -overrides -path 
DestinationPathforTheDocumentation -pretty

*) Now a couple of xml files are written to 
the "DestinationPathforTheDocumentation". You can now use monodoc to read it 
and even update it without writting XML-tags.

*) To generate a documentation like javadoc or msdn which is readable with any 
browser you have to accomplish the following last step:
monodocs2html -source DestinationPathforTheDocumentation -dest 
DestinationForTheHTMLDocumentation

the DestinationPathforTheDocumentation path is the same used in the monodocer 
step, but here it is used as source. So monodocs2html takes all the xml files 
generated with monodocer and it converts it in HTML, which then can be opened 
with the browser and looks similar to javadoc.

*) you're finished now. it's quite easy and comfortable isn't it?  ;) 
-----------------------------------------------------------------------------------

Windows:

*) the compiler needs to know that he should generate the xml  file out of 
the /// tags like <summary> ... </summary>.
This can be achived with the additional option /doc:FILENAME when calling the 
ms csharp compiler in the console or by selecting "Generate XML 
Documentation" in the VisualStudio IDE in the ProjectProperties.

*) Now a XML file should be present in the build directory (if no path was 
specified). We can use now a opensource tool to generate javadoc or msdndoc 
look like documentation.
There are several ndoc projects:
NDOC: does not work with .NET 2.0 and higher- features
NDOC 2005: fork of the NDOC project works with .NET 2.0 features
NDOC reloaded: not checked
NDOC2WORD: not checked

With the normal NDOC you can't generate doc's for .NET 2.0 projects, so have 
to use NDOC 2005. Under Windows you can install the binary, select the 
XML-File and the Assembly, select the theme (javadoc, msdn,...) and then the
program will generate a humanreadable documentation. Unfortunately there are 
some hardcoded pathnames for the location of the XSLT-files. So if you are not 
root on the machine you can't generate those folders.