Here is a listing of some of the better free soundfonts that I've found and used over the years. I acquired all of them free at sites such as Hammersound and Soundfonts.it. The problem with sites such as those is that the sheer number of available soundfonts often makes  it difficult to find those of  good quality. Here I have compiled a listing of some that, in my opinion, are the best that I've found.

You will need SFPack to unpack most of the soundfonts. You may need SFArk to unpack a few of them.

Orchestral:

Others:

Solo Violin 

Piano

Clarinet

Saxophone (Alto)

Harp

Saxophone (Tenor)

Tuba

French Horn Soft

French Horn Loud

Trombone_Soft

Trombone_Loud

Trumpet Soft

Trumpet Loud

String Section

Pizzicato Strings

Bassoon

Oboe

Flute