XNap was formerly known as JNapster (the logo survived) then forked as XNapster but is now actively maintained again and one of the most efficient opennap clients available.
XNap can automatically fetch a list of servers from napigator. It can connect to multiple servers and run multiple searches across different networks at once.
What's new in this version:
This release is mainly of interest to Windows and OS/2 users since it should make uploading on these platforms possible again. (This was actually broken in all versions after 2.3.) Apart from this critical bugfix this release only contains updates to the Japanese and the Dutch translation.