I'm using Ubuntu 12.04 now, and a few days ago, I noticed that all of the buttons for my installed Chrome extensions have disappeared. The extensions are still installed (and still enabled), but their buttons are all gone. Is this a bug, or have all extension buttons been removed as part of the latest update to Google Chrome?
Sounds like what's happened is you've clicked a little bar that is usually between the far right of the address bar (just to the right of the bookmark star) and where your extensions used to be (probably to the left of a little double arrow pointing right).
Assuming that this is what's happened, basically it sounds like you've re-sized the address bar and pushed the extensions out of the way.
If this is the case, click on the horizontal bar up there where I was talking and drag it back to the left and they should re-appear where they're supposed to be.
According to this answer, in order to make the extension buttons re-appear, you can simply drag the edge of the address bar. This will make all the extension buttons re-appear again!