...we could always give an option for the user to specify if they want a standard, easy, or tough encounter.
I'm thinking that we do it like this on the setup end:
Monster Name
Effective level
min/max appearing
Terrain (w/checkboxes for plains, woods, desert, subterranean, etc)
Frequency (common, uncommon, rare, etc)
What else am I forgetting?
Then, allow the end user to input number of party members, their level, and the terrain they are in. The site spits out a nice random encounter for them. Or, if the user so chooses, the site spits out a nice table for them. (Roll 2d10! 1-20 is goblins, 21-35 is an owlbear, etc)