The corporate jolly takes several forms:
The first, and most common, is the client focused Corporate Hospitality, approach, where company customers are treated to sport or cultural events. These are usually very extravagant champagne-soaked pitches for business. If you are lucky enough to be in a job connected to sales, but not a salesman, you may well find yourself living the high-life as you serve as a host for these events, being generally agreeable to customers, and being fed, watered and entertained at your employer's expense.
The 'company social' usually takes place around Christmas, and is noted for being far, far less elaborate than a customer oriented event. Indeed, many companies have done away with this altogether, expecting the employees to pay for the privilege of spending their free time eating at an expensive restaurant with the same group that they spend every day yearning to get away from. However, there are a few rare and valuable employers (my father is one) who use the opportunity to reward staff for a good year's work - in Dad's case, he's taken his staff to China and Lapland, the staff only being told to come with a passport, and clothes suitable for any weather conditions -- sadly this kind of jolly is almost extinct.
The third form is the teambuilding event. Rather than being a proper training session, in this form, the jolly is usually some action oriented day out, loosely intended to get members of a company or department to 'pull together' - this might be a river rafting trip, paintball games or similar - unfortunately much of the fun for which these pastimes are chosen is eliminated by sharing them with people you can't abide, although there is a certain level of satisfaction in splattering your micro-managing boss in yellow goo.
Next, and similar to the teambuilding event, in that it pretends to be about work, is the conference or expo. This kind of jolly requires staff to listen to a variety of boring presentations, before they can get down to the serious business of enjoying the food, drink and hotel.
The overseas training course is another relatively rare jolly - this is usually used to reward particularly valued employees, without being seen to give them a bonus that other employees might also expect. Here, the employee attends training that relates to their work, but in a desireable overseas location. They may be encouraged to take their spouse along, by the company booking a double room for and food the duration of the course (the spouse's fare, however, will not be paid by the employer), and will definitely be encouraged to incorporate some holiday into the trip, thereby saving themselves an airfare - although they'll be expected to pay accomodation and living expenses for themselves, during the vacation period.
Rewards are another common form, with top performing salespeople competing for holidays or consumer goods. The only way to get this kind of jolly I've found, without being a salesperson, is to work yourself almost to death, and clearly to the edge of nervous breakdown in a small company, where the owner can see your efforts, and might feel guilty enough to pay for your break -- and it isn't worth it (trust a girl who knows).
Other than these, most companies can be relied on for discount schemes, partially funded social clubs, and the occasional lunch, but with typical capitalist irony, the more expensive and desirable jollys always tend to go to the people higher up the organisation - i.e. the people who could actually afford to pay for the things themselves - where the general workforce have to do without.