I have the plain white high-sided ceramic round ones that others have pictured here that are sort of like individual souffle dishes. Have had them for 10 years & haven't used them yet - lol!!
The ones I HAVE used on an almost weekly basis are plain white ovals (approx. 3" high x 4" wide x 7-1/2" long). They're pretty much just ceramic individual "au gratin" dishes. Absolutely perfect for individual servings of pasta, flounder stuffed with crabmeat, Crab Imperial, etc., etc., etc. I bought them the same time I bought the others from a chain store called "Kitchens & Things" that unfortunately, I believe, is no longer in business.
My personal experience is that you'd get a LOT more use out of individual oval-shaped dishes than the little round ones, but for pot pies et al, you'd probably be better off with the round ones. Luckily, they're pretty inexpensive, so you might want to think about getting a set of both.