Currently there is no way to search for other users on the site. However, it is a feature that we know a lot of people are interested in so hopefully, at some point, users will have the ability to do so.
In the meantime, you are welcome to check out our Feedback forum and add your comments and votes to what has already been suggested or add ideas of your own: http://feedback.ask.com
Go to the "Ask a Question" section and type in the user's name and put Ask.com next to it, in the results, a question they answered will come up and from there you can go into their profile. It's not a straightforward search, but it does get you there!