Denatured alcohol (the denaturant varies from country to country, including methanol (methylated or meths), bitterants, dyes and so on. It's as effective as IPA on flux.
Acetone attacks very few things. Plastics are wholly unaffected. Semiconductors are made of epoxy, and other parts (like capacitors) are made in polymer boxes that aren't harmed.
Some printing may be damaged: check the datasheet if you suspect a component is not solvent washable. Capacitors are a common victim here. (This goes for alcohols as well as ketones.)
MEK also, which is a little more aggressive still towards some hydrocarbons, but mostly leaves components alone.
Chlorinated solvents are also nice, if you happen to have them: 1,1,1TCE and trichloroethylene are frowned upon these days, but also very effective.
DO NOT USE methylene chloride, a key ingredient in paint stripper. It swells epoxy!
Hydrocarbon solvents, like toluene and xylene, cyclohexane, petroleum ether (ligroin) and so on, aren't very effective, and may damage some plastics.
Tim