I have a 4gb card in my iLiad, and I might end up going for a larger card soon. I have a lot of PDF journal articles, and I will undoubtedly accumulate more as I start in seriously on my dissertation. (These are quite readable on the iLiad.) I also have manga (including PDF graphic novels from Wowio), and I prefer to have my entire fiction library on the card, as I don't have room to store many pbooks and I like to re-read favorite bits of many, many books.
In addition, the iLiad supports other applications, and I have several installed. Those also take up space.
I think that's four good reasons to want a large CF card. Whether anyone else thinks those are good reasons is up to them, of course, but they are good enough reasons for me, and it's my reader and my card, so I guess I get to decide.
