You have to create assembly and attach it to the document library u want. In the assemlbly u have to handle document library events( for eg if deletion operation is done) There is some predefined events like insert,delete..etc..i worked on this its working  fine

List of events.
---------------
Cancel Check Out - Changes made to a checked-out document are undone.

Check In - A document is checked in to the library.

Check Out - A document is checked out from the library.

Copy - A document in the library is copied.

Delete - A document is deleted  from the library.

Insert - A new document is saved to the library.

Move or Rename - A document is moved or renamed.

Update - An existing document or the value of a custom column in the library is edited.

I have created assembly. But when to try to access properties in case of delete it give error. And microsoft msdn says

"'The delete event carries no useful information to log in the fields collection"

msdn.microsoft.com/.../sharepoint_wsseventing.asp

Its working  fine for me,I am getting the file  properties which was deleted  from document library.

If listEvent.Type = SPListEventType.Delete
{
Dim site As SPWeb = listEvent.Site.OpenWeb();
Dim file  As SPFile = site.GetFile(listEvent.UrlBefore); // by using file.name property u can access the filename
}
.
.

Debug the assembly by attaching w3wp process when deleting the document in doclibrary bcos you cant print filename through assembly