Surely a very productive suffix we can slap willy-nilly onto things is -ability. In one of our older topics from work, we talked about (and I quote) availability, manageability, reliability, scalability, and secureability. In its days as a draft, the topic was referred to as the "-abilities topic," as in "Hey, who's writing the -abilities topic?"
Our company style guide (elsewhere mentioned in this post) makes a point of saying that words with the -able suffix (hence the -ability suffix) "take their meaning from the passive sense of the stem verb from which they are formed." Their example is forgettable (forgettability), which they define as "susceptible to, capable of, or worthy of being forgotten," to which they carefully add "... not of forgetting."
Their counterexample is bootable (bootability), which is proscribed because it does not carry this passive sense. Thus a bootable disk is not a disk that's "suspectible to or capable of being booted"; nah, it's a disk that is "capable of booting." So, like, verboten. Welp, Google gets 196,000 hits for bootable disk, including (paging Alanis Morissette!) articles on the Microsoft Web site.
Nonetheless, the definition of -able/-ability is, I think, generally true (the -abilities topic confirms). At least, in my nearly minute of trolling for examples, I find none that obviously do not conform, except the damnable bootability of that disk. (Although: would you say that a particular brand of paint has great paintability or that the surface to which it is applied has that paintability? Hmmm, probably both, depending on what you mean.)
I am thinking about all of this today because I ran across a blog post discussing ... well, I'll just quote and you can see:
When you're designing for Users, you do a usability study. When you're designing for Developers, you need do a a developability study.
This conforms to the definition just fine. I was pretty sure this was a singleton, a one-off coined by the blog author, but nope, you can find several thousand uses already. Moreover, although Random House does not give the word its own entry, it lists it without comment at the bottom of the definition for develop. The OED has no cite for developability, but does have several for developable, starting in 1816.
I don't have the tools for this, but it would be interesting to see whether use of -ability has increased over time; my instincts say yes, but without the numbers, that remains a hunch. But I do opine with some confidence that -ability is a productive suffix that, as I noted at the beginning, we can probably add to many (transitive-ish?) verbs (a song with excellent singability, a program with promising podcastability). Which is to say, you are free to develop your own -abilities.
 A source of common discussion is whether to include or drop the -e- in words like manageability. Our company style guide says that you keep the -e- after -ce or -ge (manageability), drop it after -e (scalability). Obviously, this is purely orthography and has nothing to do with the ability to whack the suffix onto a word. Which would be the suffixability of the, um, suffix.
PS I created this entry with Windows Live Writer!