Here are some web sites that provide some great small group leader materials:

Ampelon Publishing and click-on Small Group Resources.

Redeemer and click-on Store, then Studies and Training. *I am currently using their notes on Galatians, together with Luther’s, Dunn’s and Stott’s commentaries.

Touch Outreach Ministries and then click-on Small Group Curriculum, or Group Leader Training, or Discipleship & Equipping.

Jim Egli’s Upward, Inward, Outward & Forward is a book I would also recommend and can be purchased on Amazon