Alex Bosworth has compiled a list of Do’s and Don’t's when using AJAX.

Do Use AJAX For:

• Form driven interaction
• Deep hierarchical tree navigation
• Rapid user-to-user communication
• Voting, Yes/No boxes, Ratings submissions
• Filtering and involved data manipulation
• Commonly entered text hints/autocompletion

Don’t Use AJAX For:

• Simple forms
• Search
• Basic navigation
• Replacing a large amount of text
• Display manipulation
• Useless widgets