Best Clipart - Strength: links to clipart sites
Weakness: no content, just links
Popups? once you click enter, when you change pages, and when you leave the site
Directions: click 'enter bestclipart'

Best Free Clipart - Strength: variety of clipart
Weakness: common clipart
Popups? when you select your first category.
Directions: categories on left hand side

Best of Clipart - Strength: list of clipart sites
Weakness: no content
Popups? when you change pages, select a site, or leave the site.
Directions: 'click to enter'

By Dezigns: Web Graphics - Strength: nice appearence, fine selection of images
Weakness: no real complaints here
Popups? no
Directions: Click the word clipart at the very top of the page, In the middle of the next page, click on the bulleted category. You will then see a few images, click on one to go to the larger image of it. When looking at the larger image, you can scroll down for more related images.

CKS Info - Strength: clipart is all original(though can be found on absolutely free clipart as well).
Weakness: common clipart as mentioned above.
Popups? No
Directions: Click logo to enter, on right hand side beside the ranking list is a clipart with all original clipart below it. Click there to see the categories.

ClearQuest Clip Art - Strength: has categories for more than just clipart sites
Weakness: Not enough sites, no content
Popups? When you enter the site, when you enter the category of your choice
Directions: There are links in the middle underneath title that says art and graphics. There is also a link that says 'our picks' for a mix of their favorites.

Clipaholic - Strength: navigation is nice, clipart easy to find.
Weakness: little to heavy on pop ups.
Popups? several pop ups when you enter the site, 3 look like ad pop ups, one to a ranking list. A pop up when you leave.
Directions: once you close the pop ups, the categories are on the left hand side.