Some short "movies" about the wonderful world of the "present perfect".
1. Present perfect for experience
2. Present perfect with "yet" and "already"
3. Present perfect vs past simple (1)
4. Present perfect or past simple (2)
4. Present perfect in songs
And some good sites where you can learn more about the "present perfect"
http://www.isabelperez.com/Already%20Yet%20Still.htm (already, yet, still)
http://web2.uvcs.uvic.ca/elc/studyzone/410/grammar/ppvpast.htm (Present perfect vs past simple)
http://personales.ya.com/mjandres/archivos/GRAMMAR4&5.PDF (a little bit of everything)
Thanks a lot for your contribution.See you around