Having prints made of a JPG image file at a photo printing store is now very easy, flexible, and cost effective for the quality.  Two years ago, this was severely limited in many ways.   CostCo, Walgreens, Sam's Club, and many other stores do it.  You can get 8"x10" prints for $2 or $3, and 4"x6" prints for about 30 cents.  (Beware that once you start making 8x10 prints, you won't want to go back to looking at 4x6 prints.)  The printing calibration at different stores may vary, even within the same chain.  First try printing a few at one store and see if you are satisfied with the print quality before making many prints.  Most of these stores have a memory card reader and an interactive menu for ordering the size and quantity of prints.   Many of these will also read CD's, so you can copy images files to a CD.  There is usually someone to help.

VIP:  If you have a photo printing store make prints, be aware that they usually perform an automatic color adjustment unless you tell them not to.  If you have processed an image properly, tell them not to run their auto color adjustment.  If your image has no blue shades, for example, their auto processing will add a blue tint that you probably do not want.

Most of these stores only accept JPG files.  My procedure is to transfer image files from the memory card to my computer, eventually delete the images off of the card, edit certain images, copy the good JPG images back onto a memory card (usually an older smaller card), and then take that memory card to the store.  See the Editing Example page.

If you crop your image to a nonstandard size, then the photo processors will generally crop your print for you, thus you may lose important details near the border.  Standard print sizes are 4x6, 5x7, 8x10 and 11x14.  One option is for you to crop the original to the proper width and height ratio.  Photoshop Elements makes this easy with a parameter of the crop tool.  If you want a nonstandard print ratio of width to height, then you can increase the "canvas size" in one of the dimensions to yield a standard ratio.

You can also email your images to various sites, pay them via credit card on-line, and then they mail you the images.  Since I store my printable images at the highest resolution and quality, I don't care to email several 4MB images.

There are web services where you submit many images on-line, and then others can order prints of the ones they want.  This is convenient for large groups or reunions where different people will want copies of different prints.  I assume that the price per print is slightly higher.
 

Home Printers
A fun way to make prints is to print them on your own home printer.  You can get civilized prints off of generic color printers, but you need a "Photo" printer to get good prints.  Epson and Cannon are the tops in this category with several to choose from.  The "Photo" printers usually have 6 to 8 different ink cartridges.  HP finally came out with its first photo printer last year, surprisingly late for a company that makes good printers.  The new R300 printer by Epson makes great prints and costs about $160.  The higher end R800 by Epson is due out this month for $400, and it is supposed to be an order of magnitude better.  You can also purchase larger format photo printers for very large prints.

You need to print on high quality photo paper, which costs about 50 cents a sheet.  For best results, use the paper manufactured by the same company that made your printer.  That is a calibration issue.  Also learn how to set your printer properties so that the printer knows the exact type of paper.  The total price of making good prints at home can be expensive.  The ink cartridges are not cheap and an 8x10 print uses a lot of ink.  A printer with several individual ink cartridges is more economical because you only need to replace the ones that run out.  Do not ever use cheaper refill ink cartridges because you will see it in your prints.  Besides printing whenever you want, you can make prints of any width to height ratio.  You are not limited to 4x6, 5x7 or 8x10.  You can also print TIFF files or files in the format of your image editor by printing directly from the editing software.