Here is a list of posts that elaborate on the different pieces available.
Sheet Music
Sheet Music - Guitar - Exercise for Fingering
Sheet Music - Beginner Guitar Etude
Sheet Music - Clementi's Sonatina in C for Guitar (beginner)
Sheet Music - Miniature Sonatina for Guitar (beginner)
Sheet Music - My Grandfather's Clock for Guitar (beginner)
Sheet Music - Silent Night for Guitar (beginner)
Sheet Music - Simple Gifts for Guitar (beginner)
Sheet Music - Minuet for Guitar (beginner)
Sheet Music - Pachelbel's Canon for Guitar (intermediate)
Sheet Music - Avondale (for beginner piano)
Sheet Music - Drunken Sailor (for beginner piano)
Sheet Music - Olivia's Song (for beginner piano)
Sheet Music - Rainy Day (for beginner piano)
Sheet Music - Summer Memories (for beginner piano)
Sheet Music - When Irish Eyes Are Smiling (for beginner piano)
Sheet Music - Annie Laurie (for late elementary piano)
Sheet Music - Bonny Kate (for late elementary piano)
Sheet Music - Christmas Lights (for late elementary piano)
Sheet Music - Early One Morning (for late elementary piano)
Sheet Music - Flight (for late elementary piano)
Sheet Music - Flow Gently, Sweet Afton (for late elementary piano)
Sheet Music - Follow Me Down to Carlow (for late elementary piano)
Sheet Music - Largo (for late elementary piano)
Sheet Music - My Love is Like a Red, Red Rose (for late elementary piano)
Sheet Music - Rain Drops (for late elementary piano)
Sheet Music - Snowfall (for late elementary piano)
Sheet Music - Stormy Sky (for early intermediate piano)
Sheet Music - Autumn Waltz (for early intermediate piano)
Sheet Music - Thoughts of Spring (for early intermediate piano)
Sheet Music - Like a River Glorious (for intermediate piano)
Sheet Music - Wings of the Morning (for intermediate piano)
Sheet Music - Greensleeves (for late intermediate piano)