For now you can click the "add description" link on the build page and place any HTML you like in the build description, including links..

This is just what I'm looking for .. I need to create a link to the build page which includes the build tag. I need it to start another job by passing the build tag as a parameter.

Hi Miku- are you saying you want to run a build, then visit that build page and manually add a link like /job/otherjob/build?someparam=$BUILD_TAG ? This link then appears on the sidebar of that build page for someone to click later?

This is how I intended the original request:

• In the job configuration page, under "Sidebar Links", you would click "Add link".
• In addition to the existing text fields for Link URL/Text/Icon, there would be a "Location" combo box, with options "Job" or "Build".
• You select "Location: Build" and enter the URL "http://example.org/foo/$BUILD_NUMBER"

Now after build #55, the build page will have a sidebar link pointing to http://example.org/foo/55, and so on. So variables are substituted from the build vars.

Ok, so you'd like such links automatically added to every build.
FYI, pretty recently a "configure" link was added on build pages, so it could be possible to manually add links on a specific build after it has run..

Yes, just like Marcus said

I wrote a plugin that allows you to add links from a text file to every build. It would help maybe.
https://wiki.jenkins-ci.org/display/JENKINS/AnchorChain+plugin