As of my last knowledge update in September 2021, AI applications were making significant inroads into digital marketing to enhance efficiency and effectiveness. However, please be aware that the digital marketing landscape evolves rapidly, and new tools and applications may have emerged since then. Here are some AI applications that were relevant for digital marketing blogs at that time:

1. Chatbots and Conversational Marketing:
            Drift: Drift is a conversational marketing platform that uses AI-powered chatbots to engage with website visitors, answer their questions, and capture leads.

2. Personalization:
                     This AI platform helps personalize website content, email campaigns, and product recommendations based on user behavior and preferences.

3. Email Marketing:
              Phrasee: Phrasee uses AI to optimize email subject lines and content for better open rates and engagement.

4. Content Creation:
                ContentBot: ContentBot can assist in generating content ideas and writing blog posts or articles on various topics.

5. SEO:
              MarketMuse: MarketMuse uses AI to analyze content on your website and your competitors' sites to provide recommendations for improving SEO and content strategy.

              Clearscope: As mentioned earlier, Clearscope helps in SEO optimization by suggesting relevant keywords and phrases based on AI analysis of top-ranking content.

6. Social Media Marketing:
             AdParlor: AdParlor uses AI to optimize social media advertising campaigns, targeting the right audience for better ROI.

7. Predictive Analytics:
             Woopra: Woopra offers predictive analytics capabilities, helping digital marketers identify trends and make data-driven decisions.

8. Data Analytics:
            Google Analytics and Google Data Studio: While not AI tools themselves, they integrate AI features and data analysis to help digital marketers gain insights into user behavior and campaign performance.

9. Ad Optimization:
              AdRoll: AdRoll uses AI to optimize display ads and retargeting campaigns, helping businesses get better results from their ad spend.

10. Voice Search Optimization:
             Voice search optimization tools: With the rise of voice search, there are AI-powered tools that can help optimize content for voice search queries, such as AnswerThePublic.

11. Competitive Analysis:
            SimilarWeb: SimilarWeb provides insights into your competitors' website traffic and digital marketing strategies, helping you refine your own strategies.

12. Content Distribution:
              Outbrain: Outbrain's AI-driven content discovery platform helps digital marketers distribute their content to a wider audience.

13. A/B Testing:
            Optimizely: While not strictly AI, Optimizely offers experimentation and A/B testing features to optimize website and landing page performance.