Well, my iPod shuffle can only hold up to about 161 songs, because that's how many songs I had at the beginning of the day, and then I bought 4 more. I tried to put the songs into the iPod, but it wouldn't go in! So I had to delete a few songs that I didn't like anymore.
I think either 100 or 150 because I have an mp3 player with 1.89 gb and it holed about 150 songs. Some mp3 players/ipods hold less or more.