Altruism is an issue that presents contradictions for Libertarians. On the one hand, capitalistic principles advocated by Ayn Rand and others would seem to suggest that we would all be better off if everyone pursued their own self-interest. And indeed, empirical evidence suggests that for-profit enterprises are generally more efficiently run than nonprofits, including altruistic charities. Yet the LP itself is a nonprofit organization.
Many political parties advance candidates who will obtain significant emoluments if elected, such as an $169,300/year Congressional salary. Yet Libertarians, being unlikely to win, stand to gain no such concrete benefits from running for a Congressional seat. It appears to be an altruistic activity, then.
Even donations to the Libertarian Party do not produce a financial return commensurate with a donation to a charity, since they are non-tax-deductible. So that would seem to be altruistic as well.
Nathan Larson's essay on altruism offers a view of how it is indeed compatible with Libertarian ideals. Specifically, he hypothesizes that humanity produces a certain number of people who find greater fulfillment in altruistic activities than "selfish" ones. For them to force themselves to not behave altruistically actually is to the detriment of their genes' survival, given their specialized role in a society of related individuals.