If you develop your custom ribbon interface and actually need to implement an action handler Ken Getz has published a Ribbon User Interface for Developers FAQ, which describes the callback signatures for each ribbon control.
If you want to add a Event Handler Assembly to a specific list in Sharepoint with a Feature you have to pass a ListTemplateId.
<Elements xmlns="http://schemas.microsoft.com/sharepoint/">
<Receivers ListTemplateId="104">
<Receiver>
<Name>EventHandler Delete</Name>
<Type>ItemDeleting</Type>
…
Here's a little codesnippet to get those ListTemplateIds, just add a Reference to Microsoft.Sharepoint.dll.
string[] typeNames = System.Enum.GetNames(typeof(SPListTemplateType));
Array typeValues = System.Enum.GetValues(typeof(SPListTemplateType));
int j = 0;
foreach (int i in typeValues)
{
Console.WriteLine(typeNames[j++].ToString() + " " + i.ToString ());
}
The output of the codesnippet above should look something like this:
GenericList 100
DocumentLibrary 101
Survey 102
Links 103
Announcements 104
Contacts 105
Events 106
Tasks 107
DiscussionBoard 108
PictureLibrary 109
…
Actually these ListTemplateIds (Types) are part of the ListTemplate definitions you can find in ONET.XML