Tomato paste is often called for in recipes, but usually the amount required is less than the can they come in. The way to prevent wastage is to freeze the unused portion. I got this idea from a forum posting, whereby someone suggested using cling wrap to apportion the paste before freezing. This way, you can easily apply them in the future.
Well, I improvised on the idea by using this plastic storage box usually used for storing tiny knick knacks like nails and needles. You can easily find such a storage box in those shops selling hardware and household items. I used to store minced ginger this way too.