I currently use the Jambox. I find it's pretty good in the cabin, and sitting on the hook in the cockpit. It doesn't do very well underway, as bass will distort if you turn it up too loud, eg. when trying to hear it in the cockpit while sailing. I have heard the Big Jambox, and it sounds great, and should be plenty loud, but it is significantly bigger. I have already broken one Jambox because sometimes I connect it to an older iPod Classic using an auxiliary 1/8" mini stereo plug. Apparently, these little Jamboxes have a pretty significant weakness in the aux input plug. When you have your phone connected via Bluetooth, you will not hear music from the phone if a 1/8" stereo plug is connected to the Jambox, though you will still hear phone functions like ringing and such. Once the input jack is broken, you will never hear music from the phone Bluetooth connection, though you will still hear phone functions. I looked it up on the interwebs, and it seems relatively common. I had purchased this Jambox from Amazon, and it was fulfilled by one of their partners. So when I called Jawbone, they told me they would not warranty it, because it was not purchased from an authorized reseller. I nearly lost it. What a STOOPID thing to tell a customer - it completely erodes confidence in the brand. I don't care where it came from, you should support your damn product! I escalated to a supervisor, and they did replace the unit for me. I'm hoping the jack doesn't break again...
I picked up a Pyle Bluetooth speaker last year, because it was only $40, and was supposed to be splash resistant. I used it during a water war to play Wagner's Ride of the Valkyries on eternal loop, you know, to frighten the competition.

It's like this light blue rubberized thing, a little bigger than the Jambox. And it doesn't sound as good. So it will probably be given to one of the kids.
I heard about the Eton Rugged Rukus. It's a rubberized, splash resistant Bluetooth speaker that includes a solar panel for charging. You can also plug a phone into it via USB to charge the phone. I haven't heard it yet, so I'm really not sure how it will sound. I ordered it, and I'm hoping for it to arrive in the mail within the next day or two, to be ready for use on the first raft up of the season on Saturday. I'll report back once I've heard it. I really hope it sounds as good as or better than the Jambox.
I was in Best Buy, and there was a JBL cylinder shaped Bluetooth speaker, comes in black and red, or white and grey, or some such. It sounded pretty good from what I heard, but I think it's supposed to be placed on a table on its round end, sticking up, as opposed to laying on its side. Unfortunately, I think that would be a horrible form factor for a boat.
I have no need for a radio, or CD player. Which is kind of a shame, as I have probably 1000 CDs that never get played anymore, as they are all stored in my computer as MP3s or AAC. They used to all fit on a 160GB iPod Classic, but now the library is too big to bring everything with me. No matter, I have software called Subsonic which streams my whole library from the home computer. There is an iPhone app called iSub Streamer, that allows me to play my Subsonic server on the phone over cellular data. It's not as convenient, because making playlists is more difficult, but if I know I want to listen to an album or band, but I don't have on my iPod, I can still stream from the phone.