Okay... so from the old songs, I really love these:
* Dheere dheere machal (from Anupama)
* Aaja sanam madur chandni mein hum (from Chori-chori)
* Ajeeb dastaan hai yeh (from Dil apna aur preet parayee)
* Hothon se chhoo lo tum (Jagjit Singh, I dont know the film!)
* Sagar kinare (sagar)
* Kahin door jab din dhal (Anand)
* Tum itna jo muskura rahe ho (Arth)
* Ek ladki bheegi bhaagi si (Chalti ka naam gadi)
* Chalo dildar chalo (Pakeezah)
* Teri bindiya re (Abhimaan)
* Hum the jinke sahre (I dont know the film, but the song has a very sweet haunting spell, and I really love Lata mangeshkar's sonorous voice!)
I cant think of others. I love humming these when I work, and my co-workers have commented that these songs ring in their mind even after they leave work. None of them speak Hindi, and I think that speaks much about the richness of these songs...
I dont know whether they rocked the nation in their time, these are just my favourites...