It supports any picture file and you can choose how you will see them. Choose if you will see them ordered by tag, folder, date,... select only last week photos or the ones tagged as holidays.
Furthermore it includes a Flickr plugin which allows you to automatically upload the selected photos to your Flickr account or send them via e-mail.
My Photo Index will suit your needs, it doesn't consume a lot of resources, so it runs fast.
If you need a good picture viewer and you like tagging your photos, download and install My Photo Index, you'll love it... and it's free.