Pretty sure there is a mod out there that allows all clothes and hairstyles in every category.
But then again, there are mods out there for almost every thing on this thread that people have said annoys them, but that doesn't mean we're all going to install them all! I think I'll stick with ErrorTrap and OverWatch and that'll be more than enough for me.
I agree with Rachel about feeling the need to get every EP and SP. Part of the reason, for me, is that I've always been a jealous person and I've always hated the fact that I can't afford as much as some people. TS3 has always served as my escape from reality to help me cope with things, and not having all that's available for my sims is almost like a reminder that I have less than a lot of people. For example, something that really irritates me is when people who have perfectly fine graphics/computers demand a better system just because of, say, a tiny bit of lag. I've always had my game be very laggy since day 1, and I have to put up with it for probably the rest of my simming days.
I currently have everything up to and including TLS, I have got Pets but it isn't installed because my graphic chipset can't handle it. That alone really irritates me, and I suppose it ties into what Wednesday said about the system requirements. Even if I do get the computer I want for my birthday, which will be quite a stretch money-wise, we can only afford something that will be pretty average, and that annoys me so much. But at the same time, I know I'll be very grateful for at least being able to install Pets and then get Master Suite Stuff, Showtime and the rest of the SPs and EPs to follow, even if I'm not playing with the best of graphics. Having the whole collection means a lot to me, as silly as it sounds.