You might check out KB 34253 and the following discussion on Altirigos:
http://www.altirigos.com/vbulletin/help-desk/7300-color-coding-helpdesk-incident-grids.html

Thanks so much for your suggestion. We have added those changes in the past but maybe I should simplify my issue.

Is there a way to create a column that just says 'yes' or 'no' based on if the incident has been modified that day?

Stephen

I think you could create a custom lookup and pair that with a notification policy.  You'd just run a notification policy every. . . hour or so that would set the value of your custom lookup appropriately. 

Take a look at this article to make the lookup:
https://kb.altiris.com/article.asp?article=39840&p=1

The Notification policy would be pretty easy.

edit:  actually you might setup an incident rule that whenever an incident is modified to change it to "yes" that way you only need one notification policy to change it back to "no" not modified in 24 hours.  Maybe then you could stretch the schedule of the Notification Policy.

edit edit: Of course then you'd still need to add it to the workitem grid and do that same "coloring" action as before, but it sounds like you know how to do that.