Conventional wisdom says yes, you should use a stop bath. The stop bath is a very weak acid (similar to white (distilled) vinegar) and is used to neutralise the developing agent. This guarantees two things:
- You can be sure that you won't have any additional development happening after the developer bath.
- You won't contaminate your fix with developing agent.
Personally I've never used a stop bath - I was taught just to rinse under cold running water for several minutes. If you're using still water and agitating, frequent changes of the water in the bath is recommended. Without using a stop bath I may be getting a slow/small amount of developing happening in the print during my water rinse until all of the developer is washed off, and this is a problem that you would not have if you use a stop bath. Another plus for using stop baths is that the chemicals are very cheap. If you have a spare tray and desk space is not really worth skipping. Note that this is using RC paper. If you're using fiber based paper I would definitely recommend a stop bath as the paper absorbs developer and rinsing it isn't going to be enough to confidently arrest development.
I've checked  and  for references to stop bath and it's only the Ilford Manual of Photography that goes into any detail. Although this is describing film development, the same applies:
A plain rinse bath is very commonly employed betweeen development and fixation to slow the process of development, by removing all the developing solution merely clinging to the surface of the film. A rinse bath does not completely stop development - because it leaves more-or-less unchanged the developer actually in the swollen emulsion layer - but it does remove much of the gross contamination of the film by the developing solution.
The rinse bath then serves not only to slow development, but to lessen the work that has to be done by the acid in such a fixing bath. Rinsing then "protects" the fixing bath.
Although a plain rinse bath is all that is commonly used between development and fixation, a better technique is to use an acid stop bath, the function of which is not only to remove the developer clinging to the surface of the film, but also to neutralize developer carried over in the emulsion layer, and thus to stop - not merely slow - development.
I hope that helps. I haven't had any noticeable problems in prints using RC paper and washing for several minutes in running water or agitated water in a bath, but YMMV. Considering the price of the chemicals and the very small amount of extra work, I would definitely use an acid stop if I was going to make a print for somebody other than my own wall.
others say that your prints will continue (forever) to develop without it.
When you expose the silver halides in the emulsion/paper to light you produce a latent image on the medium. As well as doing other things like softening the emulsion in film, activating the developing agent, and also restraining the developing agent in the case of potassium bromide, the alkaline developing solution combines with oxygen to reduce the silver salts that have been exposed into actual metallic silver. The stop bath introduces an acidic environment which neutralises the developer, and as discussed earlier not an absolute necessity. The reason for this comes from the fixer. The fixing solution includes chemicals such as sodium thiosulfate which takes the un-reduced silver halides (i.e. anything that wasn't exposed to light) and makes them water soluble. This is why fixing is absolutely necessary. After sufficient fixing there will be no more light sensitive halides at all on the film/paper. To answer the question above, assuming you have properly fixed your print they will not continue to develop, regardless of whether you used an acid stop bath or a water rinse. There's simply no more light-responsive chemicals around to develop. This doesn't mean the stop bath is unnecessary though for the aforementioned reasons. If you improperly fix your print you will start to see orange/brown stains developing in the paper. For an example of what to look for in an improperly fixed print just leave an undeveloped sheet of paper out of the box for a few hours.
 The Darkroom Handbook, second edition, 1984, Michael Langford, Ebury Press
 The Master Printer's Workbook, 2003, Steve Macleod, Rotovision
 The Manual of Photography (formerly the Ilford Manual of Photography), sixth edition, 1972, Focal Press