Here is the March update of the applications I have seen using the Seesmic API (or around Seesmic), please let me know if you know more than I missed, thank you in advance. If you want to create apps on Seesmic too, join our Google Group (please ask and we add you), already 132 members of the group.
Plugins and widgets
Seesmic official widget builder
WordPress plugin (by @douglasskarr)
Netvibes widget showing last videos (by Romainhuet )
Firefox sidebar with last Seesmic videos (by Steve Purkiss)
Seesmic google mashup (to add your videos to iGoogle) (by ?)
Google desktop application by Bob stewart.
A business card like signature by Pierre Lechelle
(just replace with your username) <br /><img src=”http://ntrm.net/seesmic/carte.php?username=fred2baro” /><br />
add “firstname.lastname@example.org” in your gtal/jabber and type help. You can track any term in the video title with it
SeesmicAir (by @Critter, now Seesmic team member)
mp4 or mov video upload in Seesmic
Post to Seesmic from hundreds of phones via Shozu
QIK.com live video client on Nokia N95 upload videos to Seesmic (title in the Qik video now complusory)
Totally experimental prototype of Seesmic mobile on Nokia n95
Stats and most active Seesmic members via API
A tentative, not updated. Who will do the first Seesmic top members board in number of followers, videos etc?
Other cool stuff using or not using the API
The Seesmic mosaic is a very cool idea created by laza using pictures of Seesmic videos
Seesmic racavatars logos of Seesmic members based on our raccoon logo (by Kmeron)
Portrait galerie by Moox
Interactive Seesmic faces by Tiil
Seesmic World Project by @critter
I know there are many people working on other mashups or apps, will announce them as soon as they are out. Let me know if I missed anything and thanks fred2baro for gathering already most of them on your french post.