Well, so I start with my own
Think outside the box to finish
http://steamcommunity.com/sharedfiles/filedetails/?id=121714444

a new one of a friend
which could calculate
http://steamcommunity.com/sharedfiles/filedetails/?id=116227179

you may like this one too
http://steamcommunity.com/sharedfiles/filedetails/?id=121107875

How about some coop maps? For new repulsion gel useage, play my test "jumpers". For single player and coop combined, play any of my confinement tests (specifically confinement 3: freedom, because it's challenging yet simple). I cant post a link at the moment, but they're fairly new in my workshop so they shouldn't be too hard to find.

Both of the following are tiny, simple maps that introduce a (relatively) new way of using portals, which can be quite challenging to discover. Can you?

http://steamcommunity.com/sharedfiles/filedetails/?id=118255102
http://steamcommunity.com/sharedfiles/filedetails/?id=120529859

I have a lot of maps with new / unusual consepts. Here are some of them:
http://steamcommunity.com/sharedfiles/filedetails/?id=102317554
http://steamcommunity.com/sharedfiles/filedetails/?id=114011223
http://steamcommunity.com/sharedfiles/filedetails/?id=137172453
http://steamcommunity.com/sharedfiles/filedetails/?id=112777041
http://steamcommunity.com/sharedfiles/filedetails/?id=112946868
http://steamcommunity.com/sharedfiles/filedetails/?id=114566525
http://steamcommunity.com/sharedfiles/filedetails/?id=117331115
http://steamcommunity.com/sharedfiles/filedetails/?id=112768822

This uses something that's known as a T-flipflop latch.
http://steamcommunity.com/sharedfiles/filedetails/?id=132778147

Well, "new concepts" is what I try to place in every map I make X) So if someone is motivated to play some of them and tell me if you consider it as new or if you already found it in some other maps, here are my collections ^^

I have been making a ton of new consepts or at least using them if you want to see some

http://steamcommunity.com/id/RFUN/myworkshopfiles/