1. Building a Cryptocurrency Wallet: Use PHP to develop a cryptocurrency wallet that allows users to securely store and manage their digital assets. Implement features such as account creation, transactions, and balance tracking. You can also integrate with external APIs to fetch real-time market data and facilitate cryptocurrency exchange.

2. Implementing Smart Contracts: Smart contracts are self-executing contracts with terms written into code. Use PHP to develop and deploy smart contracts on a blockchain network. Implement contract logic and automate the execution of contract terms. This can be useful in various scenarios such as supply chain management, real estate transactions, and insurance claims processing.

3. Creating a Supply Chain Management System: Create a supply chain management system using a blockchain network and PHP. Allow participants in the supply chain to record and track the movement of goods, verify authenticity, and ensure transparency. Use PHP to develop the frontend and backend components, and integrate with the blockchain network to store and retrieve data.

4. Developing a Decentralized Voting System: Develop a decentralized voting system using blockchain and PHP. Implement features such as identity verification, vote casting, and result tabulation. The use of blockchain ensures transparency and immutability of voting records, making the system resistant to tampering.

5. Building a Document Verification System: Use PHP and blockchain to create a document verification system. Allow users to upload documents, create digital signatures, and store document hashes on the blockchain. This ensures the integrity and authenticity of the documents, making them easily verifiable by anyone with access to the blockchain network.

6. Creating a Tokenized Asset Exchange: Use PHP to develop a tokenized asset exchange platform. Allow users to create and trade tokens representing real-world assets such as real estate, art, or commodities. Implement features such as token creation, issuance, and trading. The use of blockchain ensures transparent and secure ownership tracking of the tokenized assets.

7. Developing a Decentralized Marketplace: Build a decentralized marketplace using PHP and blockchain. Allow users to buy and sell goods and services directly, without the need for intermediaries. Implement features such as product listings, order management, and dispute resolution. Use blockchain for secure and transparent transactions, and PHP for developing the frontend and backend components.

8. Implementing a Blockchain-based Identity Management System: Develop a blockchain-based identity management system using PHP. Allow users to create and manage their digital identities, and securely store and share identity attributes. The use of blockchain ensures data integrity and privacy, while PHP can be used for user authentication and identity attribute management.

9. Building a Blockchain-based Crowdfunding Platform: Use PHP and blockchain to develop a crowdfunding platform. Allow project creators to create fundraising campaigns and investors to contribute funds. Implement features such as campaign creation, payment processing, and fund distribution. The use of blockchain ensures transparency and accountability in the crowdfunding process.

10. Creating a Blockchain-based Supply Chain Finance Platform: Use PHP to develop a supply chain finance platform that leverages blockchain technology. Allow companies to request and receive financing based on their supply chain data. Implement features such as credit assessment, financing request processing, and repayment management. The use of blockchain ensures transparency and immutability of supply chain data, reducing the risk for financiers.