Best camping Hack and/or Fad

I find it very interesting looking through very old posts on this forum and others regarding mods, home made solutions, creativity, etc.

Just wondering what some of the best or most memorable things have been for many of the seasoned RVers. What has worked and what have you seen come & go?

For example; PVC sign holders, Bucket lights, flower pot lights, toilet paper tube fire starters, and so on.

Thanks!