Widgets in Odoo

1. char_domain
2. contact
3. email
4. float_time
5. gauge
6. handle
7. html
8. image
9. integer
10. mail_followers
11. mail_thread
12. many2many_binary
13. many2many_kanban
14. many2many_tags
15. many2manyattendee
16. monetary
17. one2many
18. one2many_list
19. priority
20. progressbar
21. radio
22. selection
23. sparkline_bar
24. statinfo
25. statusbar
26. url
27. reference
28. button
29. textbox
30. one2many_list
31. many2one_list
32. many2many 

eg :

<field name="company_id" widget="selection"/>
 <field name="state_ids" widget="many2many_tags"/>
<field name="sequence" widget="handle" />