There are a couple of things I've made for myself that I use frequently but have never reviewed them because they're pretty simple, but I thought I'd share them with you here... They are all made using towels.
The first two are items I made for when I shower at the gym - a spa wrap and a hair wrap. Much better than using the one small thin towel my gym provides as "towel service"... I'll even use the hair wrap rather than a shower cap if I'm not washing my hair.
The spa wrap was made using the instructions found here.
The hair wrap was made using instructions similar to these.
The other thing I made is a bathroom organizer that I hang inside the shower. It hangs from the shower curtain rod and keeps small items handy. It can also be thrown in the washing machine when needed. It was made using instructions found in Sew Simple Volume 2 (2006).