There are forums which deal with videos, and ones where people lists sale information. Both have a numeric measurement to them - duration and price.
It would be useful if a tag can be set to contain a numeric value, and one can filter / sort topics based on it.
For example, for a site listing videos, a #duration tag can be attached with a value in minutes. One can then use parameters such as tags:duration=>10 to search for topics containing videos longer than 10 minutes.
Some range-filter sliders can probably be set in advanced search to help users utilize the feature.