Most groups that have daily builds create a penalty for breaking a build. Some examples:
Having a kitty for a post project party to which each person who makes a wrong check-in will contribute a fixed amount ($5 or something).
Some groups give out lollipops to each "sucker" who breaks the build. This developer then has to tape the sucker to his office door until he fixes the problem.
Microsoft developers on high-profile projects such as Windows NT, Windows 95, and Excel have taken to wearing beepers in the late stages of their projects. If they break the build, they get called in to fix it even if their defect is discovered at 3 a.m.
What penalty do you have in your organization for breaking builds and failing smoke-tests?