Yep. Actually, there is an industry-set standard specification for the dimensions and whatnot of slimline drives, and every slimline drive should fit these specs. If there's a slim drive that doesn't then chances are, it's either highly specialized (like a slot-in drive for Apple laptops) or more likely, because it is indeed an industry-standard slimtype drive, but enclosed in some kind of proprietary casing.
I don't know of any places that sell slimline DVDRW drives (people have looked for them online before, without any luck). This is because the slimline drive market is highly specialized and the only people who really buy them are laptop manufacturers and not regular users.
I have found slimline CDRW/DVD-ROM combo drives online, though. The LiteOn LSC-24082K is a fine drive (I have one that I replaced my laptop's CD-ROM with), and can be had for $64 from Newegg.com if you live in the USA.