I did my research to add "share buttons" to my flash games a while ago, and I'm going to share the list of formatted links that I gathered.
If you did your own research you can share what you found out, so we can build a repository of social/share network simple-URL api.
(Facebook can get extra info from some special meta-tags in the HTML head)
URL: URL to your site.
TITLE: Custom title for your site (not supported by all).
facebookhttp://www.facebook.com/share.php?u=URL&t=
TITLEtwitterhttp://twitter.com/home?status=URL+
TITLEmyspacehttp://www.myspace.com/Modules/PostTo/Pages/?u=URL&t=
TITLE&c=<a+href=
URL>
Title</a>
delicioushttp://delicious.com/save?url=URL&title=
TITLEstumbleuponhttp://www.stumbleupon.com/submit?url=URL
For Flash/AS3 guys:
_makeURLForPage = new Object;
_makeURLForPage["facebook"] = function(URL:String, Title:String):String {
return "http://www.facebook.com/share.php?u="+URL+"&t="+Title; };
_makeURLForPage["twitter"] = function(URL:String, Title:String):String {
return "http://twitter.com/home?status="+URL+"+"+Title; };
_makeURLForPage["myspace"] = function(URL:String, Title:String):String {
return "http://www.myspace.com/Modules/PostTo/Pages/?u="+URL+"&t="+Title+"&c=<a+href="+URL+">"+Title+"</a>"; };
_makeURLForPage["delicious"] = function(URL:String, Title:String):String {
return "http://delicious.com/save?url="+URL+"&title="+Title; };
_makeURLForPage["stumbleupon"] = function(URL:String, Title:String):String {
return "http://www.stumbleupon.com/submit?url="+URL; };
Usage
theURLToOpen = _makeURLForPage["facebook"](urlencode("http://my.site.com"), urlencode("My awesome site"));
Regards