70. Simple XLink support
This is used for links in XML documents.

71. XML-RPC
Simple API for doing XML-RPC.

72. Built-in SOAP API
Fairly extensive set of SOAP functions are available without any extra libraries needed.

73. PNG alpha transparency
For making transparent images.

75. MNG image support
An animated image format, usually used for animated PNG images.

76. Supports 'favicons' in any image format
Supports any image format that Mozilla supports (GIF,JPEG,PNG,MNG,XBM,BMP,ICO). You can even make them animated if you're insane.

77. Display icons in tabs and address bar
Displays site icons in the tabs and in the address bar. This is off by default in various builds.

78. Available for more languages/locales
Mozilla is available for many different languages, including ones you've never heard of before.

79. Support for standard event handling
Supports the standard capturing/bubbling event model.

80. Support for additional DOM0/DOM1/Core features
Supports almost all of DOM0 and DOM1.

81. DOM2 namespace handling
Supports the various DOM methods that deal with namespaces.

82. DOM2 Style interfaces
Supports most of the standard DOM style interfaces.

83. DOM2 TreeWalker interface
The TreeWalker interface is used to navigate through a document.

84. DOM2 Range interface
Supports the Range interface for grabbing blocks of text.

85. DOM3 XPath interface
Supports retrieving elements using XPath expressions in HTML/XML/XUL documents.

86. Address field in full screen mode
In full screen mode, there is an address bar to navigate to other pages.

87. Can set size of printed output
This may vary based on your printer, but one can scale the printed document or fit it to the page. Useful for those sites that are just a bit too large.

88. Can bookmark groups of pages (in tabs)
You can bookmark a set of pages and them open them all at once in multiple tabs.

89. Can search bookmarks
You can search bookmarks without having to search through your file system.

90. Easily create and add custom components
XPInstall can be used to easily install custom components, using an install script written in JavaScript. No special tool required except a ZIP utility.

91. Supports finger protocol
Can use the finger protocol. This has been disabled in newer versions of Mozilla.

92. Supports data: URLs
data URLs can be used to embed data in a URL.

93. HTTP Pipelining
Allows for better performance when viewing pages.

94. Supports JavaScript getters/setters
For adding custom properties to objects.

95. JavaScript supports strict error checking
Which means displaying errors for things you didn't think were errors. (Think Perl's strict mode)

96. Easily accessible preferences file
Preferences are all stored in a single file (prefs.js) which one can easily edit to add custom settings which have no UI.

97. Preferences can be moved around easily
One can easily copy preferences, bookmarks and other settings to another system as they are all stored in a single directory.

98. Various security related features
Surely you knew Mozilla had better security features?

99. Supports irc protocol
Supports the irc: protocol for opening Chatzilla

100. Open Source
So keen developers can always find out exactly why Mozilla behaves the way it does, or change it if they so desire.

101. Bugzilla
This is Mozilla's bug tracking system, where you can find information about problems you encounter and can help get them fixed.

Giant lizards are cool
Much more exciting than a blue e.