That hardly needs a module when there is the -s operator,

$ perl -e'printf "%s %.0fK\n", $_, (-s)/1024 for <*.png>'
2002_04_16_035041_shot.png 7K
2002_04_16_035143_shot.png 2K
2002_04_24_194156_shot.png 21K
2002_04_24_194408_shot.png 20K
2002_04_24_195557_shot.png 22K
2002_04_24_202442_shot.png 17K
noise.png 7K
pm_shot.png 7K
unix_time.png 376K
Zaxo_nn_shot2.png 9K
zaxochair.png 26K
$
[download]

It sounds, though, like you want the server to read file sizes on the client machine. You can't do that over http. You need a client willing to run your javascript or whatever to do that.