Hi,
if he's 80, his eye-sight and hearing probably aren't as sharp as they were, so books, CDs are prob out.
Does he have any interests/hobbies, so that you could buy a present in those areas?
How about a case of nice claret, which he could enjoy in his own time. Or even take him to lunch/dinner somewhere special.
For my mother's 70th, we asked all her friends, relatives, ex-co-workers etc to write an anecdote/story/memory of her and include an old photo if they had one. We then bound all those memories into a book - she says that's the bext present she ever got!