Functional bikes. Not Porn not Anti

On the wikipedia page for CX bikes there's loads of interesting design features listed:

Frame materials are selected with an aim to produce a lightweight, yet stiff and responsive frame. Lightness is prized for ease of carrying while running. A cyclo-cross racer may lift or carry his bike as many as 30 times in one 60 minute race, increasing the desire for a lightweight bicycle. Aluminum frames were popular in cyclo-cross bicycles long before they became commonplace on the road. Today the most popular material is aluminium with carbon fiber being popular at a professional level and steel and titanium being favorites amongst riders searching for a smoother ride and a longer lasting frame.

Cyclo-cross frames require clearance for slightly wider (generally 30–34 mm) tires and the debris and mud that is picked up by them. They are typically very simple, often eschewing bridges between the rear stays. Compact geometry frames with sloping top tubes are less common than on road bicycles due to the need to carry the bicycle easily on the shoulder. Top tube (rather than bottom bracket) routed derailleur cables help combat the build-up of mud. Some specialist cyclo-cross bikes also have a higher bottom bracket to aid clearance over rough ground; extra clearance could prevent toe clips from dragging while re-mounting after an obstacle. This is less common as clipless pedals have become the norm for cyclo-cross.

Typically, the frame geometry is a bit more relaxed than that of a road bike, not as upright in the seat tube, which allows for more shock absorption. Also, the wheelbase is a bit longer, which provides a more stable feel over rough terrain, and helps keep the rider's feet from contacting the front wheel during a tight turn....

There are slight geometry differences between road and cyclocross bicycles; cyclo-cross bikes tend to have slightly higher handlebars for a more upright position as aerodynamics have little importance in a cross race. A second set of brake levers on the tops, called top mount brake levers, are favored by some competitors. The top tubes of cyclocross bike frames typically have an ovalized or flattened bottom profile to provide greater comfort when riders need to shoulder and carry their bikes. In general, with a change of tires and gearing a cyclo-cross bike can double as a perfectly adequate road racing machine. However, most cyclo-cross racers prefer clipless mountain bike pedals for their easy dual-sided entry and mud-shedding abilities.