Sorting by Manufacturer and Product Category

Using the 'Who's Online' feature, I noticed a customer had loaded a page that allowed sorting via two drop-down menus - Manufacturer and Category. I was surprised as I didn't know that was possible. I've tried to replicate, or rather discover how my customer accessed this search/sort functionality on my site, but I haven't been able to do it (which is rather embarrassing!). I'd love to point people to this great feature but I can't find how to access it!

If someone could let me know how this is achieved/accessed, I'd greatly appreciate it.

Thanks.......

When viewing a category's products, there are a couple filter/sort pulldown menus available at the top of the list to limit results by manufacturer or the letter their name starts with. These can be turned off/on via switches in the admin area if you'd rather not offer them.

Additionally, clicking on a column title allows sorting by the information in that column.

Additionally, if you have the manufacturers-list sidebox enabled, customers can choose to view your store via manufacturer choices.