When you have several lines of business within one company, you run the risk that if one of the lines doesn't do well, it can take down the fortunes of the others. In addition, you may find that some of your colleagues want to be involved in only one or two of the lines of business; no all of them. In that case, it might make sense to start separate companies, as their ownership structure will differ.
Definitely speak to a local business attorney and accountant about your options (and whether an LLC as an entity is the right one for what you want to do). From a business perspective, however, tread carefully when trying to pursue multiple activities under one "roof," as it were. You want to be sure that all of the owners agree on the time, money and effort it will take to bring each one to fruition.