The present invention generally relates to compositions, including liquid compositions, for the delivery of pharmaceutical agents and other beneficial substances, e.g., in various forms, including but not limited to a liquid, patch, cream, lotion, or gel. For example, some aspects of the present invention are generally directed to formulations comprising deep eutectic solvents. In some cases, such formulations may exhibit surprisingly low melting points, for example, such that the formulations are liquid at ambient temperatures. Such formulations, in some cases, may be useful for facilitating absorption of pharmaceutical agents or beneficial substances that are poorly soluble in water. Also, in certain embodiments, such formulations may be substantially free of water, which some pharmaceutical agents, such as aspirin, can be sensitive to. In addition, in some cases, the formulations can be present in various delivery vehicles, such as patches, creams, lotions, gels, and the like. Such formulations, in some cases, may be useful for containing pharmaceutical agents or beneficial substances that are poorly soluble in water, or are sensitive to water, etc. Accordingly, such formulations may be liquid without necessarily being aqueous, and accordingly can be administered to a subject orally, in liquid form. Other aspects are generally directed to methods of making such compositions, methods of using such compositions, kits including such compositions, etc.