what if a motherboard has no VGA port?
 

Some of the mobos I'm looking at appear to have no VGA port. In that case, what would I plug the monitor into? Every computer I've owned had a VGA port in the back.

AGP or PCI-E graphic card
Many people get a better graphic card anyway, so they just save some money on that.

Most enthusiast/aftermarket mobos do not include the circuitry to drive a display (the "graphics card"). If you don't have the circuitry, you won't have any use for the connector (but you usually will want to plug in a monitor, so you will usually want to get a separate card which will include the connector).

There are pros and cons to having a separate graphics card:

1. A seperate card allows the end user the choice of various performance levels, with this being the only route for users who want the highest 3d performance.
2. For the highest performance solutions, power consumption and the resulting temperature rise are an issue, and a seperate card allows the room to install an effective (weighty, expensive, noisy...) cooling solution.
3. Traditionally, the 3d performance of motherboard graphics solutions has been very weak (although recently some exceptions have come to market which have a performance that is only a bit weak) and on board solutions tend to share main memory.

1. The total installed cost of on board solutions can hit a lower price point, and, compared to a high performance solution, can cost very much less.
2. The power consumption of an on board solution can be lower and is likely to be very much lower than a high performance solution. As a result cooling performance is likely to be obtained with less airflow, fewer fans and possibly less noise.

So, in a sense, its horses for courses, but if you need 3d performance, separate video card has advantages. If you do not need 3d performance, then there is a strong argument for one of the better on-board solutions (and many pre-packaged business solutions do exactly that). Some of the AMD/ATI solutions allow you to combine the on board and the separate card approaches, but I have no evidence that this actually works under Linux (if that's an issue).