Nettles are always painful...

Another appropriately humiliating thing that can be done LD is him telling you what to wear for a particular day. Say, for example, a shopping trip, he could ask you to wear very sexy underwear. If you wanted the public aspect of humiliation he could also ask you to wear a very short skirt and low cleavage/see through top so that the underwear is potentially visible to people in the shop.

Body writing is a common thing as it is usually secret unless someone else other than your Master routinely takes your clothes off

Make full use of digicams and webcams (the wonders of modern technology - we no longer have to worry about our photographs being seen by lab techs in the photoshop and possibly reported to the police...) as well as voice recorders and other technology. I remember one academy task was to record yourself having an orgasm and post it on the public board for people to listen to.

As well as online, you can also use the phone and VOIP phones make this a lot cheaper now if you have one. A hands free kit/microphone and speaker set for your PC is useful for this as you can do other things while still talking to him.

Other online tasks I have done:

Housework while dressed submissively/naked and bound with elastic bands round ankles, knees, elbows, wrists etc to make it more difficult. Can also be gagged or plugged for this.

Position practise. 5 minutes in each of the gorean positions (I used a CD which had a playing time of exactly 5 minutes for this but you can use an alarm timer or similar). A similar one is 'furniture practise' where you assume a position as a piece of furniture and wait for a set amount of time with a tray on your back or holding a lit candle etc.

Taking sexy or erotic pictures to send to the dom. You in different positions, dressed/bound/gagged as he asks. One, for example, involved being displayed as a 'table centrepiece'. As an added humilation, he can also demand that you post these somewhere public (like this site...)