Apple's website quotes ipod nanos holding 1000 songs. This sounds about right because I have a 64 MB mp3 player and it can hold almost 20 songs, so proportionally speaking, this means a 4 GB could hold around 1200 songs. 1000 songs or 3500 pictures
I think that depends on how long a song is or what songs you have or what other extra stuff you have. But I know it's over 200 About 45, actually. 1 GB, which is 1,000 MB, holds 250 songs. 180 MB = 180/1000 GB = 0.18 GB. So 180 MB would hold 0.18 X 250 songs, or about 45 songs.