The other day I took part in a conversation in the Ecademy blogosphere about how keeping in touch with your contacts became progressively more difficult as the number of contacts grew.
Now Seth Godin has suggested that keeping up with everyone, or with every article even in a "thin slice of a thin topic" is impossible. In his blog article "Warning: the internet is almost full" Seth comments that there is simply too much information and that even if the internet isn't physically full, we are.
Which brings me to an answer to the question of keeping up with contacts: you can't. You can offer a range of ways, through blogs, newsletters, web pages, tweets, and whatever, to let the people who are interested in what you do keep up with you. But if Seth Godin's right (he often is) and our attention span is under such attack, you're going to have to be doing really interesting things for anyone to be really interested.
Now I need to make sure that I do something interesting every day!