SharePoint Permissions Cheat Sheet

The following is a list of the default permission levels organized from greatest to least permissions and relating them in a concise hierarchical manner.  You can modify these however you want; but I recommend creating new permission levels instead or modifying the default permission levels in order to avoid confusion.  

Microsoft has grid versions of this, but this format is much simpler.
Permission level details are available here: Technet

Full Control - Owner

• + Manage Hierarchy

• + Design

Design

• Apply Themes and Borders

• Apply Style Sheets

• Override list behaviors - checked out to other user

• + Edit

• + Approve

Manage Hierarchy - Hierarchy Managers

• Override list behaviors - checked out to other user

• Manage and Enumerate Permissions

• View Web Analytics Data

• Create Subsites

• Manage Web Site

• Manage Alerts

• + Edit

Edit - Members

• Manage Lists

• Add and Customize Pages

• + Contribute

Approve - Approvers

• Approve Items
• Override list behaviors - checked out to other user

• + Contribute

Contribute

• Add, Edit, Delete Items

• Delete Versions

• Browse Directories (explorer view)

• Personal info, views, and web parts

• + Read

Read - Visitors

• Open Items

• + View Only

View Only

• View Versions

• Create Alerts

• View Application Pages

• Self-service Site Creation

• Browse User Information

• Use Remote interfaces

• Use Client Integration Features

• + Restricted Read

• -  Open Items

Restricted Read

• View Items

• Open Items

• View Pages

• Open web/list/folder

Limited Access

• Browse User Information

• Use Client Integration Features

• Open web/list/folder