TriangleDraw is brilliant for sketching logos. You can quickly create designs that can be used for branding on letterheads or on your website.
Install via App Store - available for iPhone + iPad.
TriangleDraw Gallery - see what can be done using this app.
Greetings from Simon Strandgaard, the developer of TriangleDraw.
Feel free to write to me: hello@triangledraw.com.