150 is fine for most purposes, but this service isnt really good for converting a large amount of video... (its still the best way ive found to get video on my new zune)
maybe you can have a paid-not-free service for us heavy users? maybe for xx$ per month/year/whatever we can upload multiple files for conversion, and have a much larger filesize limit (like 1GB or so)
and then, once the subscription money rolls in, you can remove some ads from the site (like that "YOU WIN A FREE IPOD!" audio-one thats so annoying! i mean, i've no problem with visual ads, but those loud audio ones are really obnoxious.)