Danny Boy is a famous ballad set to an ancient Irish melody with lyrics by English songwriter Frederic Weatherly.
For Flute and guitar duet.
Early intermediate.
With downloadable mp3's for audio help (one with both the Flute and guitar and one with guitar only).
With guitar tablature. With melody line. With lyrics.
Pages: four pages (score and Flute part)

Mauro Giuseppe Sergio Pantaleo Giuliani (27 July 1781 8 May 1829) was an Italian guitarist, cellist, singer, and composer. He was a leading guitar virtuoso of the early 19th century.
This is the seventh of the set of 16 easy and pleasant duets for violin and guitar composed by Mauro Giulani at 1810.
For Violin and guitar duet.
With downloadable mp3's for audio help (with both the Violin and guitar and one with guitar only for practicing the Violin).  With guitar tablature.
Pages: Seven pages (2 pages both Violin and guitar, 1 pages Violin part, 2 pages guitar part, 2 pages guitar with guitar tablature part), 2:20' min.

Flow, my tears is a lute song by John Dowland (15631626). Originally composed as an instrumental under the name "Lachrimae pavane" in 1596, it is Dowland's most famous ayre, and became his signature song.
For duet  Flute and guitar. 
Intermediate.
With guitar tablature. With lyrics. With melody line. 
With downloadable mp3's for audio help (one with both flute and guitar, one with guitar only).

Pages: 4 pages (3 pages score, 1 page Flute part), 3:20 min.

"Just As I Am" is a well-known hymn, written by Charlotte Elliott in 1835,
Here is an arrangement for Violin and Guitar duet. With lyrics and Melody line.
With guitar standard notation and Tablature.
Three pages (two pages both guitar and violin, 1 page violin)
With downloadable simple mp3 for audio help and practice the Violin.

Mauro Giuseppe Sergio Pantaleo Giuliani (27 July 1781 8 May 1829) was an Italian guitarist, cellist, singer, and composer. He was a leading guitar virtuoso of the early 19th century.
This is the eighth of the set of 16 easy and pleasant duets for flute and guitar composed by Mauro Giulani at 1810.
For Flute and guitar duet.
With downloadable mp3's for audio help (with both the Flute and guitar and one with guitar only for practicing the Flute).  With guitar tablature.
Pages: Four pages (1 page both Flute and guitar, 1 page Flute part, 1 page guitar part, 1 page guitar with guitar tablature part), 1:15' min.