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
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.
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.
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...