fileformat.info:

• Toplevel list of UniCode blocks
• Selected CJK
• Detailed list without pictures, link from hexadecimal to picture

 
Online dictionaries from English to something:

• mdbg.net
• part of chineselanguage.org (gone)
• chinese-tools.com (works, but doesn't show tones)
• ktmatu.com which interface from WAP here
• (many links to browse)

 
Input methods:

• Use mouse to draw character, server matches purely by shape: yellowbridge.com
• Descriptions of various input methods, but no other online shape-recognizing services: wikipedia
• Given character(s), show decimal UniCode(s):
  chinese-tools.com (requires JavaScript, works only for Chinese)
  PHP demo (no JavaScript needed, and works for ALL non-USASCII text: Enter any text into any of 3 fields in second (POST) form, submit it, verify it shows same text you entered, then look at page source to see the HTML for the UniCode.)