Some great tips, many of which I had no clue about!
Tomatoes - don't react well to cold. Store tomatoes at room temperature until completely ripe, and afterwards keep up to one week in the refrigerator. Remove stems before placing tomatoes in refrigeration. To prolong the tomato's shelf life, store in plastic bag with large holes for good air circulation, and put a paper towel (or small kitchen towel) next to the tomatoes to absorb excess moisture. Personally, I prefer a plastic box lined with a towel, for compact storage.
Bell peppers - more cold-tolerant than tomatoes, but this is only true for the red, yellow and orange - not the green (which basically aren't ripe). A firm pepper in good condition can be stored in the refrigerator up to ten days. The nylon bag + paper towel idea can be used in this case too.
Cucumbers - a bit problematic, because on the one hand, the temperature in most refrigerators is too low for cucumbers; on the other hand, they can't be stored outside the refrigerator, because they tend to wrinkle and shrivel up very quickly. The best compromise appears to be, again, storing them in a plastic bag with a paper towel. Always remove the residue of the flower attached to the cucumbers, because rot usually begins to spread from there.
Eggplants - like cucumbers, don't react well to cold, but can't be stored outside of the refrigerator for a long time either, so it's better not to stock on them too much time in advance. Persoally I only refrigerate them during the summer months. It is recommended to buy light eggplants with firm, shiny skin. Heavy eggplants have many seeds, which are a source of bitterness.
Lettuce - lettuce, like other leafy vegetables, needs storage in very cold temperatures close to freezing point. In your average refrigerator, it will survive in decent condition for approximately a week. To prevent wilting and allow air circulation, it's best to store lettuce in a plastic bag with tiny holes.
It's important to remember that the upper shelves of a refrigerator are slightly colder than the lower shelves - it's particularly true for older refrigerators (such as ours). Therefore, if storage at room temperature isn't practical, we store cold-sensitive veggies in the lower shelves.
To be continued...