I agree with BlackBart -- really depends on what you intend to do with your rig. Personally my truck 'had' to have XM, but not via the OEM headunit. The user interface on the OEM headunit bites, so I put in a Roady, but I am about to upgrade to a MyFi. The screen has more date and is more effective with my aging eyes.
I put off getting a truckbox for months, and my wait paid off as some other folks on this site identified the best options. Using their advice/experience, my truck now has a UWS slimline box, mounted on a Back Rack safety bar.
The safety bar was bought 'cause my truck is a working rig. It is used heavily for my own needs. Additionally, many of my coworkers here on the East coast own sedans, minivans, or SUVs, but I'm one of two with a fulsize truck. So when anyone needs to haul something, my Titan is their first stop for assistance. After nearly putting a piece of rebar throug the back window, I ponied-up for the BackRack. Besides being very effective in shielding the back window, it also has a mounting option for truck boxes (which I use) and they give the truck a certain tough-guy appeal from the rear. Silly, I know, but the look of the truck from the back and side still makes me smile when I see it. Some of my Ford/Chevy/Dodge friends still comment on the new 'look'. 8>
Bugreflectors are a handy option, but are not 100% effective. I estimate that roughly a third less bugs hit the windshield, enough to make them a worthwhile option for you to consider. Being a cheap Scots B*st*rd I bought the OEM when I should have bought a 3rd party solution. Oh well...
My most recent option has been a set of Weathertech window visors, and I really like them. They help cut down on rain/moisture drips during rain storms and have allowed me to keep my A/C usuage down because I can now keep the windows cracked without adding too much noise to the cab.
My next option is a CB. Why a CB? I drive up and down I-95 once or twice a month and frequently run into truckers and traffic issues. Well, those truckers always know where the state police are, and they always seem to know what the traffic slowdown is all about. (Anyone who drives through or around DC knows what I'm talking about.) I have been using an emergency CB, but it just does not have the broadcast/reception range that I need. I can hear a trucker within 1/2 a mile, but that range is not enough, so a permanent solution is needed. Of course, I'll research on this site before making any decisions. 8)
Hope this helps,
Jack