3 of 9 (also called Code 39) is certainly the easiest of the various "flavors" of barcode to use because it can code both numbers and letters (some barcode formats are strictly numerical) and because it doesn't require any special math to create the correct code (some codes require calculated check digits, etc.). So you can easily barcode just about ANYTHING that you want to code. Lower case characters, spaces, and other special symbols can require a two character code.

The best/simplest barcode scanners are the "keyboard wedge" type of scanner. It just hooks between your keyboard and the computer and anything you scan enters the system exactly as if you had typed in the data.

So, if you wanted to (and were feeling particularly masochistic) you could barcode the entirety of "War and Peace" and scan it into the computer little by little.

The Raiser's Edge Mail module can automatically generate special code numbers that can be printed as a barcode and then scanned into a batch in a special barcode field. That single special code will then automatically enter several pieces of information into the batch record. For instance when we at the Memphis Zoo print membership renewal notices we print the RE generated code. Then when we scan that code into a special field in the Batch module RE automatically knows which constituent and which membership is being renewed (some constits have multiple active memberships, a regular zoo membership plus one or more animal adoptions, for instance).

RE can also generate special codes for phonathons, etc. that when scanned will automatically enter the fund and appeal information that was designated when the phonathon forms were created in the Mail module.

If you have something that RE won't automatically do then you could certainly create barcodes with any needed information on a field by field basis. The start & stop character for Code 39 is an asterisk. So the "text" in the barcode font would be:
*CONSITID*
*FUNDID*
*APPEALID*

If you are using Microsoft Word 97/2000 then you will want to turn off the "Autoformat" feature before trying to create 3 of 9 barcodes. The asterisks used for the start & stop character will be interpreted by Word's Autoformat feature as a command to make the characters bold which can have highly undesireable results! In Word go to Tools/AutoCorrect. On the "AutoFormat As you Type" tab uncheck the "*Bold* and _italic_ with real formatting" box. For safety, uncheck this box on the "AutoFormat" tab also.

Another alternative is that many of the laser scanners can be programmed to automatically add a suffix to each successful scan. So you could program your scanner to "type" a tab character after each successful scan. Be careful though. Some scanners send the control character for the tab instead of the "keyboard scan code" for the tab. The control character for a tab (Control-I, if I remember correctly) is also a keyboard shortcut for some function in Batch and will bring up a new window for that shortcut.

Make certain you get a high-quality scanner that can do an actual "keyboard scan code" and not just an ASCII control character for the tab.

As for the font size to use for the printed barcode, that depends on several factors. You need good printing resolution and good scanning resolution. A good laserprinter and a good laser scanner can easily create and read a 12 point barcode. A "wand type" scanner might need a larger barcode. We print our membership renewals on a 9-pin dot-matrix printer, so we have to print the barcodes at about a 30 point size. Anything smaller doesn't print enough horizontal resolution to get an accurate scan. Paper quality can also affect how small you can print a barcode (cheap paper can smear ink or let the toner flake off).

A good resource for more information about barcodes in general is the online "Bar Code Primer - Introduction to Barcoding" from Worth Data USA at http://www.barcodehq.com/primer.html.

A good resource for purchasing barcoding equipment is http://www.systemid.com/.