A large collection of free to use graph papers:

Downloadable and very printable, I find these PDFs extremely useful.

  

Squares

• Grid
• Multi-weight Grid
• Dots
• Crosses
• Light Verticals
• Grid Lined
• Axonometric Perspective

Triangle and Hexagonal

• Equilateral Triangle
• Octagonal
• Hexagonal
• Hex Dot
• Semi-bisected Trapezoid
• Iso-Dots
• Tumbling Block
• Diamond – Trapezoid
• Equilateral Triangle Dots
• Variable Triangle

Circular and Polar

• Circular – Hex Pattern
• Circular – Grid Pattern
• Polar Graph Paper
• Spider Graph Paper

Brick, Asymmetic, and Specialty

• Asymmetric
• Brick
• Moorish
• “174 Paper”
• Engineer’s Paper
• Accounting – Ledger
• Log / Semi-Log
• Polar
• Storyboard
• Music Notation
• Fretboard Diagrams
• Number Line
• Celtic Knot
• Perspective

Writing and Note-taking

• Notebook
• Lined
• 3-Line Penmanship
• Double Lined Penmanship
• Cornell Lined
• Cornell Graph
• Cornell Music
• Chinese Character Guides
• Calligraphy Guideline
• Genkoyoushi (Japanese Character)

Link: Free Online Graph Paper / Grid Paper PDFs via www.incompetech.com