Because is very useful and powerful, it is considered as a standard approach to design modern web-applications.Using Ajax you can develop interactive solutions for lightboxes, form validation, search, tooltips, navigation and tables. Always keep in mind its drawback in terms of usability and accessibility. Extensive Ajax means that you can easily confuse your visitors giving them to much control and features.

1. AJAX AutoSuggest: An AJAX auto-complete text field

2. AJAX Autocompleter / script.aculo.us library

3.  AJAX AutoCompleter

4. Ajax autosuggest/autocomplete from database

5. Ajax dynamic list

6. AJAX inline text edit 2.0

7. AJAX & CSS Flickr-like Editing Fields

8. AJAX Instant Edit

9. 14 Tab-Based Interface Techniques

10. AJAX Menu Widget

11. amCharts: customizable flash Pie & Donut chart

12. PJ Hyett : The Lightbox Effect without Lightbox

13. MooTabs – Tiny tab class for MooTools

14. Dynamically loaded articles

15. AJAX Datetime Toolbocks – Intuitive Date Input Selection

16. AJAX Calendars

17. AJAX Floating Windows

18. AJAX Star Rating Bar

19. Ajax poller

20. AJAX HistoryManager, Pagination

21. AJAX Login System Demo

22. AJAX image preloader

23. AJAX Tooltips: Nice Titles revised | Blog | 1976design.com

24. DZone Snippets: Store, sort and share source code, with tag goodness

25. Max Kiesler – mHub : Ajax and rails examples & how-to’s

26. Ajax Rain: growing showcase of AJAX-examples.

27. MiniAjax.com: a showroom of nice looking simple downloadable DHTML and AJAX scripts.

28. My Favorite Javascripts for Designers: Blakems.com ?

29. Draggable content

30. AJAX Shopcart

31. How to Create an Animated, Sliding, Collapsible DIV with Javascript and CSS

32. How to Create Digg Comment Style Sliding DIVs with Javascript and CSS

33. SmoothGallery: Mootools Mojo for Images | Full gallery

34. AJAX Unobtrusive Popup – GreyBox

35. AJAX LightBox, Sexy Box, Thick Box

36. AJAX TableKit

37. AJAX Table Sort Script (revisited)

38. Ajax newsletter form

39. Really easy field validation

40. Transparent Message