CANCELED: NBC has handed a pink slip to "Providence," after the Friday series suffered from low ratings. A final two-hour episode will air Dec. 20. On a happier note, the new NBC dramas "American Dreams" and "Boomtown" have both been extended to full seasons, with nine additional episodes added to the initial 13-episode commitment. Meanwhile, on HBO (which, like PEOPLE, is part of AOL Time Warner), the veteran series "Arli$$," is folding its tent after eight seasons, though its creator, star and executive producer, Robert Wuhl, 51, is expected to develop a new series and other projects for the cable network, according to the Hollywood Reporter.