One Skein Wonder, 20 Ideas from Bulky to Ethereal | Fiberchats 

Here are my suggestions of what you can make with a single 100 grams skein of yarn in any weight.
Bulky:
1. Eiru Headband by David Van De Kamp (Episode 17 of Fiberchats)
2. Wister Hat by Courtney Kelley (free pattern of Ravelry)
Worsted:
3. Drop Stitch Scarf by Christine Vogel (free pattern on Ravelry)
4.Daniel's Hat by Ysolda Teague (free pattern of Ravelry)
DK:
5. Leave-Me-Not Mitts by Myla Vayner
6. Vanilla Socks by Crazy Sock Lady Designs (free pattern on Ravelry)
7. Easwas Hat by Kate Davies Designs
Sport:
8. Airy Cowl by Myla Vayner
9. Requited Hat by Romi Hill (Episode 57 on Fiberchats)
Fingering:
10. Artesian Shawl by Romi Hill (Episode 57 on Fiberchats)
11. Ol' Reliable Top Down Socks by Tanis Lavallee
12. Bright Eyed Becky by Chic and Regal Knits ( Episode 21 on Fiberchats)
Lace:
13. Seascape Stole by Kieran Foley (free pattern on Ravelry)
14. Morvarch Shawl by Lucy Hague
15. Fladda Shawl by Elizabeth Williamson (Episode 29 on Fiberchats)
Cobweb, Gossamer and Beyond
16. Esha by A Passion for Lace( aka Monique Boonstra, Episode 20 on Fiberchats)
17. The Third One by A Passion for Lace( aka Monique Boonstra, Episode 20 on Fiberchats)
18. The Fourth One by A Passion for Lace( aka Monique Boonstra, Episode 20 on Fiberchats)
19. Little Secret by A Passion for Lace( aka Monique Boonstra, Episode 20on Fiberchats)
20. Princess Shawl by Sharon Miller