or, how to get my attention in a negative sense:
Create an LJ which deliberately disguises your identity. Run across my journal. Let on that you knew me in the past. Refuse, when asked directly, to let me know who you are. Start asking questions about my life and my plans. Be revealed -- because there are some people on LJ who do have the mapping -- to be the one and only one ex with whom I am not on speaking terms, thus neatly reinforcing the idea that it's better not to be on speaking terms with you this decade, either.