[NYG]

Can I download the Slacker app if I don't have a data plan? Would it work?

[amazinglygraceless]

No:Appears to only offer OTA download
No: from the Slacker website -
# BlackBerry OS 4.5 recommended (OS 4.3 minimum requirement)
# Data Plan or Wi-Fi (An unlimited Data Plan is recommended for streaming)

[FollowMeSoccer]

Short answer, yes.

Long answer, don't. It requires an OTA and data to work. So in theory, you could use it but you would pay a lot of money in extra data fees unless you get a data plan or your BB as wi-fi.