I've recently added or corrected mapping of the
LDS temples in the USA, Canada, and Europe.
I'll be adding or correcting LDS church buildings
in San Diego this summer.

I've downloaded some Digital Orthphoto Quadrangles from seamless.usgs.gov,
which are .3m resolution rectified aerial color photos,
all in the public domain, and quite useful for mapping,
e.g. reviewing the Tiger-based data around here.

They just ask for attribution/recognition,
so here it is: I will improve/review the Central San Diego
part of OSM using the DOQs provided by the US Geological Service.
Thanks, Feds.

Philip J. Erdelsky has put up a good mapping and overview resource
for the North Park community of San Diego at efgh.com,
including freely usable bitmap maps based on GPS, lists of businesses, etc.
I will use his material to "review" more of the tiger mapping data,
and improve coverage.

I've just acquired an AMOD AGL3080 data logger for $60,
and I am fairly happy with it. I'm correcting the map
around South Park and North Park in San Diego,
plus surroundings as I happen on them.
Walkabouts and eyeballing for gross corrections,
GPS for fine measurements.

The Tiger mapping data that initialized OSM
in this area has many streets listed that were
only contemplated or are extrapolations along
straight lines of streets that are actually intermittent.
The interruptions by canyons here necessitate many adjustments.

I intend to fix up problems in central san diego, california,
using direct observation, since I have no gps, yet.
The Tiger mapping data has lots of inaccurate connectivity
where streets leap canyons when they shouldn't, etc.
My wife and I take exploratory mapping walks,
marking up a map printout.