iPage is the registrar that Lenka used to register her domains. The are a decent domain registrar, but their hosting support is in its infancy. When I tried to run our site from their hosting services, I had significant difficulty getting to run on their platform.
Dotster is one of the better known registrars. It used to be called 000domains.com. I am moving away from Dotster due to predatory billing practices, specifically upselling you on ancillary services like privacy, transfer protection and so on. If you release the domain, they continue to bill you for those services even though you no longer own the domain. If you discover these over billings, you are required to call them, sit on hold, then have a non-English speaking "assistant" promise to reverse the charges, which to their credit, they have always done. Aside from the billing issues, I have never had a technical problem with them.