I assume you mean for a digital camera/camcorder? If so, you can take pictures/film on them until the card if full, and if you have a laptop and card-reader, you can put this information from the card onto the laptop and then take the information off of the card.
If not, then you'll have to stick it out with the full card or buy another one, although 512MB is quite a bit
Short answer is you could:- 1) Go to a photoshop and get them printed, then reformat the card and start again. 2) Carefully delete the pictures you've taken that you don't like in the hope you make enough room for more. 3) Drop the image size to fit more pictures in the space. 4) Stick the sd card in your wallet for later and buy a new one, fortunately SD cards are getting much cheaper now click here .
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