Somewhat related, I see no point to using a pseudonym for most websites. Posters are often careless enough with their personal info that a clever reader can connect pseudonyms to real names. Posting under your real name eliminates this false sense of safety, and provides a mental "do I really want to be responsible for this text?" safeguard against poorly edited posts.
I have danieljackoway.com mail setup with Google Apps, and I have it setup so that *@danieljackoway.com forwards to <my actual email>@danieljackoway.com. I generally respond from <my actual email>@danieljackoway.com, but I don't give it out online at all. (It is on my business cards, though.) My normal pattern for signing up for stuff is to signup with foo.tld@danieljackoway.com. And then if they won't stop spamming me or they leak my email to something spammy, I know who they are and I can setup a filter so I don't see any of it.
I also use it to tell where people are emailing me from, to an extent. So in my hn profile is hn@danieljackoway.com (which, if I ever get popular enough that I need to start filtering hi@danieljackoway.com to skip the inbox, I can give precedence to).
I also have a label that gets applied to things that are actually sent to <my actual email>@danieljackoway.com
Though I must say that I've been surprised at how many (theoretically) legit places have leaked my email address. Like when aweber got hacked, I suddenly started getting spam on a whole bunch of aliases.
If my address gets leaked but I still want to continue getting email from a company, I update my email address with them to include the (then) current month and year (so companyMMYY@) and then I disable the old alias. So far, I haven't gotten any spam at any of these new MMYY aliases so it kinda feeds my suspicion that their mailing list must have been hacked.
To be fair though, the spam recognition on gmail is so good that I don't even have to worry about hiding my email. I rarely see more than 1 spam email a month.
Spamfiltering, on the other hand, just works.
If the non-spam protected alias gets leaked, I simply change it - and it continues to work, with less spam protection.
When dealing with sites I don't trust much, I instead make up an alias specific for that site so I'll know to trust them even less if I get spam to that alias.
fogbeam@gmail.com
prhodes@fogbeam.com
Have at it...