In most manual transmission vehicles it is possible to shift gears without use of the clutch. This is done by matching the engine output RPM with the rotational speed of the vehicle's transmission output. Please note that this can only be done when the vehicle is in motion, the clutch must be used when starting from a dead stop.

Method One of Two:
To Upshift

1
When the car is in motion and when the current gear is in shifting range, take your foot off the accelerator. This will relieve the tension in the transmission. Immediately afterwards, pull the shift lever out of gear.

2
Push (or pull) the shift lever in the direction of the desired gear, applying light pressure against the desired gear. (NOTE: The amount of pressure required can vary: Too much pressure and the gear can slip in prematurely, resulting in gear grinding. Too little pressure and the gear won't slip in all the way, resulting in gear grinding.)

3
Once the engine RPMs have dropped to match the rotational speed of the transmission output, the shift lever should slip into gear.

4
Once the car is in gear again, you can continue normal driving.

Method Two of Two:
To Downshift

1
When the car is in motion and when the current gear is too low to maintain proper power, take your foot off the accelerator and then pull the shift lever out of gear.

2
Lightly tap on the accelerator once to raise the engine's RPMs to around 2000-2500 (depends on the transmission).

3
While the engine RPMs are dropping, push (or pull) the shift lever in the direction of the desired gear, applying light pressure against the desired gear.
Once the engine RPMs have matched the rotational speed of the transmission output, the shift lever should slip into gear.

4
Once the car is in gear again, you can continue normal driving.


http://m.wikihow.com/Drive-a-Manual-Transmission-Vehicle-Without-Using-the-Clutch

Please are there any advantages driving without using the clutch

This should only be done if your clutch fails & you need to manage the vehicle to a safe / desired location.
It's not something to be done at random.

Doing this is not advisable. The day I had a problem with my jalopy clutch, and I called the mechanic who told me to push as he shifts into gear 4 and he used the ignition. He used his own technique to shift till he got to the workshop but when I got there 5 minutes later, the whole car was boiling like he'll just for a kilometre and a half. I think it's because it revs up all the time and that's wicked on the transmission.
I won't advice that no no no.