Here are some links to companies that are nice to know about... just in case you don't have enough stash! (Enough stash... what's that?!?)

Charles Craft - quality fabric and other stitchables
Crafter's Pride - lots of premade items for stitching -- great gifts!
Eterna Silk - an economical silk floss in over 500 colors, plus new overdyes
Hobbyware - publisher of a fantastic computer program for cross stitch designing
Kreinik - my favorite metallics, and silk floss too
Lakeside Linens - hand-dyed washable linen in colors like Attic Lace, Autumn Gold, Silver Fir -- gorgeous!
Mill Hill - beads, buttons, and treasures that really dress up a design
Silkweaver - you know you want to be in their Fabric of the Month Club! Awesome hand-dyed fabrics and more.
Zweigart - beautiful linens, stitch bands, and other fabrics. They have new "vintage look" linens!

Here are various companies that produce beautiful overdyed cotton floss. Check 'em out!
The Gentle Art
Weeks Dye Works
Six Strand Sweets
Needle Necessities
Olde Willow Stitchery
Crescent Colours