Industry groups that hold events in Hollywood…

• Actor’s Advantage Showcase: Collective of actors, comedians, independent film makers, acting teachers, writers and film festival directors, bringing actors directly in front of casting directors and agents. Weekly workshops. Cost varies.
• The American Society of Cinematographers: Committed to educating aspiring filmmakers and others about the art and craft of cinematography. Frequent events.
• The Caucus for Producers, Writers, & Directors: Linking the best of Hollywood and Television’s creative content providers with the rest of the web world. Frequent events
• Digital Media Artists, Los Angeles: Association for professionals creating imagery for video, film, and other media using desktop tools. Meets monthly, third Tuesday of the month.
• Editors’ Lounge: Networking and resources for post-production professionals. Meets monthly.
• Edwards Skerbelis Entertainment: Online Hollywood and Film Workshops.
• Film Independent: Non-profit organization dedicated to helping independent filmmakers. Screenings and events held on a regular basis. $95/year.
• Greater Los Angeles Writers Society: Non-profit association dedicated to mentoring writers in all genres and levels of expertise. Monthly meetings and special events, forth Saturday of the month.
• Independent Filmmakers of the Inland Empire: Like-minded individuals serious about film making, centered in the Inland Empire. Meets monthly and special events, first Wednesday of the month.
• Institute for International Film Financing: Independent social-impact organization dedicated to bridging the gap between the worlds of filmmaking and finance. Meetings on last Thursday of the month.
• LA 3-D Club: Group of 3D stereo photographers that meet in Pasadena on the third Thursday of the month. $30 membership.
• LAdobe: Aims to share knowledge of all things Adobe, and present the best speakers and events for the Los Angeles tech, creative and development communities. Monthly meetings every fourth Thursday at 7:00pm. Free.
• LA Writers Group: Writers workshops and 8-week programs. Cost varies.
• Los Angeles Final Cut Pro User Group: Meetings held every fourth Wednesday of the month.
• Los Angeles Women in Music: Dedicated to fostering equal opportunity for women and men in the music industry. Cost varies. Various monthly meetings. 
  
• Media, Entertainment, Technology, and Arts Association (META): Community of media professionals sharing creative inspiration, information and tools. $198 membership.
• National Association of Record Industry Professionals: Created specifically for record industry professionals, NARIP promotes education, career advancement and good will among record executives. Membership options from $9.95/month to $395/year.
• The Network Studio: Warm, creative and professional environment for actors to meet casting directors, agents, managers and producers through workshops.
• Tubefilter News: Growing the audience of web television. Meetings fourth Thursday of the month.
• ScreenPlayLab: Hollywood film and TV professionals that meets monthly in Beverly Hills on the second or third Thursday of the month. FREE.
• Showbiz Store & Cafe: Retail store in New York and Los Angeles catering to the specific technology needs of the media and entertainment industry and supporting local filmmakers and emerging talent through our industry-related events, workshops, special discounts and scholarship programs. Cost Varies.
• The Scriptwriters Network: An educational, non-profit, volunteer-driven organization created by writers for writers and industry professionals. $90 annual membership.
• Women in Film: Aiming to empower, promote and mentor women in the entertainment and media industries. Membership cost varies.
• Writers Guild Foundation: Founded by Writers Guild members to benefit writers in the entertainment business. Cost  varies.
• The Writers Junction: Weekly events promoting both the solitude of writing and the value of social contact throughout the day.