where to apply icons ?

hehe ... I've just thought of a neat idea: for a link to a page on another site, get the other site's favicon (if it has one) and use it as the link icon ... :-)

thanks Ray - so there is! it took me a while to find, but in the process I noticed how many contrib modules are used to do different icon things ... so here's a quick round-up:

• Context Links module allows you to easily create links to context-related material using a simple markup syntax. The links are indicated by either linking the text itself or by inserting a specific string or icon that links to the related information.
• External Links is a small module used to differentiate between internal and external links. Using jQuery, it will find all external links on a page and add a small icon indicating it will take you offsite. You may optionally make all external links open in a new window.
• Outgoing links filter This is a simple filter that adds in a configurable CSS classname to all outgoing links (e.g., links that point to a *different* website). What's so useful about that? Well you can then easily add a little icon next to each link indicating that it takes you to a different site. Or you can use some unobtrusive JavaScript to hook in some useful effects, warnings, or whatever you want.
• URL icon Display URLs with corresponding favicon. A simple filter which checks the content for <a>-elements and automatically fetches and stores the corresponding favicon.ico if available. Generates and stores a CSS-file to stick the favicon to the URL at display time.
• User Badges module allows each user to be assigned 'badges' which can be displayed as a series of iconic images. A common use will probably be to display the badges along with the user's information within forums, comments, or node postings. These badges can be assigned individually by the administrator or attached to a role so that, for example, all users in the 'admin' role will show the 'Administrator' badge which could display as a graphic letter 'A'.

From this I can see how an iconification API might well draw support from all these module maintainers/ developers. I can also picture an icon.module (including the API) which would be the basis for a number of 'plug-in' modules for various iconfication functions ... ?

One thing they all seem to have in common is 'themeing' links. Can anyone thing of a case where an icon would be used for anything that isn't (part of) a link?

@ #4.2 iconic decoration ... hmm; yes, I can see how 'attribute' or 'metatag' icons can be useful in non-link areas.

I'm a little bit alarmed by the word 'decoration' ;-) ... IMO the main purpose of icons is they are recognised at a glance, and have a consistent meaning through-out a given website (at least) - a kind of informatic visual short-hand. This is quite different from 'decoration' whose effect is to distract or make the eye linger. Am I being to narrow minded about this ?

Node_title icons: eg content-type, updated, unpublished, unmoderated, etc. As a node_title is content, it would never be entirely replaced by an icon ?

Block_title icons : interesting idea ... eg display user role 'badges' in the Navigation block_title ? or, as blocks are often module-specific, show an icon denoting the module eg taxonomy ?... would you ever want to use an icon to entirely replace a block_title ?

Form_element_label icons : are you thinking of recurring form items like a 'Postal Address' fieldset legend, a 'Phone Number' field label, a 'Birthday' field label ... etc ? (are these not something like XML datatypes ... ?)

Prefixing labels with icons is a relatively easy CSS theming task : I've started a couple of CSS iconification tutorials in the theming handbook.
Replacing labels (strings) with icons using CSS is not so easy ...