Do you know some GUI tool to create Hardlinks/SoftLinks/Junctions?
I don't think you will find a more feature-rich and well-documented utility/add-on than Hermann Schinagl's Link Shell Extensions found here: http://schinagl.priv.at/nt/hardlinkshellext/hardlinkshellext.html
Truly everthing else that I have read and used pales by comparison.
NTFS Link provides an explorer extension for creating hard links.
Have a look at Junction link magic
Have a look at symlinker.
I haven't found a shell extension to create symbolic links yet (NTFS Link, suggested by Adam, can only create hard links and doesn't have x64 shell support).
I've used symlinker as well. It's simple if you have a slight understanding of the differences between varying symlinks. It doesn't however scan for symlinks, but I really don't need that function anyway.