I use my arduino for all sorts of thing. I personally like the ping ultrasonic sensor, it has sample code on the parallax website and it is usually spot on (the only time the measurement is off is because of operator error). For an LCD they are all pretty much the same, just make sure that if you do not have the mega, get one of the LCD's that only need three pins. I don't know where mine is from, I got it with my digisparks. For good servos, I would try looking at RC car websites, they have some of the best, and highest power servos in a small form factor that i've used. For stepper motors, try looking for people throwing away printers, typewriters, or things like that; take them home and strip the motors out of them, printers usually have a surprising number of stepper and non-stepper motors in them. And lastly, I use the plain jane arduino ethernet shield. Just thought i'd put in my $0.02