WHAT WITH ALL the discussion these days about who will or won't run for high city office in 1978, many residents may not realize that some other important local elections are upon us. And if you're not already on the city's voter rolls, this weekend is your last opportunity to register to vote in the Nov. 8 school board and Advisory Neighborhood Commission elections. There's an added attraction this time - two ballot questions about amendments to the city's charter.

Seven school board seats - enough to make a difference on the 11-member board - are up this year. It would be a shame if interested citizens had to forfeit a chance to vote because they hadn't registered. In addition to two at-large seats, there are contests for one seat each in wards 2, 3, 4, 7 and 8.

Voters also will be making decisions about their single-member ANC districts - with all 367 district seats up. In almost half of these districts, there are no announced candidates, which may be an unfortunate result of recent congressional denials of ANC operating funds and inattention from city hall. Still, this neighborhood experiment deserves support, and write-in candidates are permitted.

The ballot questions on election day will be about initiative-referendumand recall amendments to the city charter that have been approved by the city council and the mayor. The changes would allow citizens to introduce legislation and remove elected officials from office.

But the last days to register are today and tomorrow. Registration (at the District Building) closes at 5 p.m. Sunday. Or you can register by mail if it is postmarked no later than Oct. 9. So whether or not you choose to show up at the polls on Nov. 8, the time to reserve that option is now.