Other than obnoxiously begging for unnecessary donations each year...
But I don't think there are a lot of better options for Wikipedia to ask for money.
Realized the same thing about a year ago about SPLC (splc.org). Once I realized how much cash they have I saw that my contributions would have more effect elsewhere. I like what splc does: help discriminate which groups are hate groups and which aren't, among others. But they simply don't need any more money IMO.
"The Internet Archive is a US 501c3 non-profit organization."
So, similar to Wikipedia.