On a more practical level, a personal site is a place to put stuff related to what I'm doing or working on and could almost be called a "portal" tying together sites and information relating to projects I'm involved in. That might not matter a lot to people who are primarily interested in sharing pictures of their favorite pets, but for someone who is involved in a "cause" or who is otherwise trying to persuade or promote, that can be an important function of a personal site. It helps to have a consistent, central site that organizations I work with and media people can go to even though the particular set of projects and organizations I'm working with at any given time is always changing.
How much email feedback to you receive from your site? Is it mainly positive or negative?
I get a fair amount; it's at least 95-98% positive.
I figure that if someone doesn't care for a site, they'll just go on to the next. Most people won't spend the time to look through a site (let alone comment on it) unless there's something there they find interesting.
Almost all the negative comments I get fall into one of two categories:
A) My webpages are more primitive than dirt.
Which is true--there's no Flash animation, no background sounds, no JavaScript, no mouseovers, and not even a single animated .gif. I'm not a "web designer"; I'm more a writer who knows just enough HTML to get by. At the moment, I count 274 HTML pages on my personal page and they were all written either in Notepad or, more recently, Arachnophilia which is a freeware editor that's more convenient for editing multiple files at once. Arachnophilia highlights HTML tags in color and chides you for omitting the closing quote, but I use it basically the same way I used Notepad before.
B) My personal page is full of pictures of myself, things I've written, and pages about what I've been up to or involved in. Don't I ever put up anything else?
Well, um, I don't have any pets (decided I didn't have time to take care of them or pay attention to them, plus I have a lot of friends with allergies), no matter how much I've worked on it, I'm still a lousy artist, and I have this ongoing bugaboo about respecting copyright law.
Often enough I do find myself worrying about the same thing, but I also want to keep adding to and updating my site regularly. I spend a lot of time around myself and don't have to worry about model releases, copyright issues, etc. When it comes to movie clips, trailers, music videos, and the like, I have agreements that cover my use of the material and internet distribution, but obviously that's easier to accomplish when it's my music video or movie than when it's, say, Britney Spears' or Brad Pitt's.
What I do to fight down my own "who on earth would want to see yet more pictures of me?" reaction is by reminding myself that nobody *has* to go to my website or load up my pages if they don't want to see them. I figure that if they want to see pictures of Britney or Brad, they could always go to Britney's or Brad's website.
Even when it comes to things like the weightlifting/ bodybuilding dictionary I write (nothing on the web is ever "written" in the past tense; it's always in the process of being revised and added to, so the verbs occasionally need to be changed to reflect the medium) it's just easier for me to walk down the two flights of stairs to my gym and take a picture that I need for a particular term than it would be to find one that someone else had made and then get permission to use it or verify that it's not protected by copyright.
Now after rambling on about the negative comments, I feel like I should come up with something clever (or at least equally long-winded) to say about the postive comments I get, which really do vastly outnumber the negative ones. That's itself illustrative of one problem I have, which is that I often can't think of much more to say in response than, "thanks!" or "glad you liked it; I should have another page on [insert something relevant here] done in the next couple of weeks"
Actually, I'm absolutely the worst at getting back to some of the people who have written the most kind and helpful comments, just because they really do deserve more than a little one-line response, and, as mentioned above, I do suck at keeping up with email. I don't know of a good solution to that problem, except to hope that writers won't be too offended if it does take me a quite a while sometimes to respond.

