Bulk domain availability check & registration, where?

[Fli]

Where can we easily check more domains availability and register more domain at once?
Currently im using Godaddy bulk register (its accessible from top menu "Domains")

[Clonderis]

Personally I am quite happy dealing with http://Sibername.com/ Domain Registrar. Their pricing is not the cheapest around, but they are well-known, reliable and trustworthy.
They offer nice specials and lots of unique domain name extensions at reasonable rates.