Wanted by me:
Portal Gun
MacroSaver
JVS Portals
Used by me, properly ported:
AutoJet
Duplicator
JVS Doors
Used by me, ported, but still has bugs:
MultiTool Gun and Wand.
Not used by me, but still good.
Those Custom Hats
Stunt Plane
Not needed anymore but still where good:
Wrench Events
I think those are addons that change the gameplay in a nice way.
There are more, of cause, but those are the ones that come to my mind.
And for the topic:
I think people should stop posting ported stuff in the add-ons section, if they want something ported, they should do it themselfs, or wait for the original author to do it.