Activity Streams are an extension to Atom feed format to add info about actor and verb to the feed, i.e. who-does-what. This makes it possible to just subscribe to certain activities of the originator or a feed, and filter just for the activities of interest.
To a certain extend an icon that indicates an Activity Stream-enhanced RSS feed competes with the very well established RSS icon. Hence it is not an easy task to propose such an icon. No reason not to try it anyway:
If you do not spot it at once I failed. But here is a hint: Look for 16x16 pixels bottom right.
Each icon is a visual abstraction of a concept or idea. The idea behind my waves are an electroencephalogram (EEG) or seismograph, that tracks several sensors. Each for a special aspect of the observed body. You can also see it as a river, where the user from the shoreline can scoop out some information of interest.
Why green? Green is bio and bio is life. And green is not orange.
> Discussion at AS's google group
To the extent possible under law, Matthias Müller-Prove has waived all copyright and related or neighboring rights to Icons for Activity Streams. Hamburg, 8-Oct-2009.
|16x16||42x42 with 1 pixel transparent frame|
|#3 - blue is also not orange|
|#2 - draft, do not use|
The lines are based on the 'almost equal to' charachter of the font Bitstream Vera Sans. But Helvetica works as well if you move the lines a bit together. To me it is important that the left and right edges look straight cut. Many other fonts have more brush-like narrow ends.