Is it permissible to suggest recording lectures on Islamic topics such as supplication, uploading them to an Islamic website, and displaying advertisements for other Islamic websites to collect funds, then donate these funds to Palestine?

This is a good suggestion that combines proselytization (da'wah) with giving charity to the needy and supporting the oppressed. Our brethren in Palestine are in dire need of money, and they are more deserving of charity than others. This suggestion falls under the category of guiding to goodness and enjoining the truth.