I have found that frozen melon (honeydew, cantaloupe) freezes well for smoothies. I have yet to try watermelon, but I don't think that is very promising. The texture of the frozen cantaloupe or honeydew in the smoothies is very fine and smooth.
I have froze bell peppers as well, but for soups, sauces, and other cooked items. They are very soft and mushy when thawed, but I like the flavor they impart to certain cooked items. They chop well frozen, but forget about it if they're thawed.
Ditto for rhubarb. I wash it, cut it into 1/2" chunks and bag in quart bags. Easy to break up and take out what you want. Yes, it thaws mushy, but we use it all winter in bran muffins and other baking. Great in Rhubarb Almond Cake.
frozen bell peppers and jalapenos are excellent for making stuffed peppers. I use a combination of rice, tomato sauce, meat such as ground round, chicken & even fish. Fry up the stuffing & keep it in the fridge. Pull some frozen whole peppers out of the freezer (you need to remove the tops & insides before freezing) stuff & pop in the microwave with a little shredded cheese. Perfect "fast food."
I make lots of soups so I really like to freeze peppers and onions. Just cut them into chips. lay them on cookie sheets, freeze and hen put them in containers so I can take out as many as I need or want at one time. Also I like to take tomatoes, dip into boiling water, squeeze the tomatoes keeping skin into bags contin enoughn for one time, squeeze the bag, let the air out, seal and lay flat for use in soup or sauces.
I also like to bread squash, lay them on sheets to freeze, put them into bags and take out what I want to fry and they are really good.
Been wondering about freezing spices. Any comments?