I am hoping to be able to use Data Driven Pages in ArcGIS 10 to create mapbooks. I have used (30-day trial) software from MapLogic called "Layout Manager" (one time intial cost $1200 - my City cannot pay). It is the industry leader for the moment. One strong capability of that software is indexing. Lets say you create a "Fire District Map" showing the city's roads, streets, hydrant locations, and more. THERE MUST BE AN INDEX FOR EVERY MAPBOOK (if desired). The index software figures out for every segment of road or streets which pages of the mapbook contain these streets. Long Hill Ave may appear on 6 different pages. It must list those pages. Constitution Boulevard will also appear an many pages. The index will tell you which pages to look for that Boulevard. Huntington Circle will be on one page only. The index confirms which page. The index is usually located as a separate section at the end of the mapbook. The user should have options as to how the index is formated (font, font size, comma delimited page numbers, 1-2-3 column formating, in alphabetical order with option for a break and large capital letter between each alphabet group, page numbering, and so forth.
A fireman going to a fire needs to quickly see which page(s) of the mapbook he needs to turn to to get to the fire and find the hydrant location. It may be a matter of life or death. An INDEXING CAPABILITY is VERY IMPORTANT!
[To my knowledge, ArcGIS 10 does not have this capability yet.] I have been asking ESRI about this.