Didn't He go into synagogues?Why would he do that when he didn't have a building to worship in? He did worship post much everywhere, afterall, proclaiming god in all places.
An LDS person can donate to tithing, which is basically simply building up the Church.
Anyone can donate to fast offerings, feeding the hungry.
Anyone can donate to humanitarian aid, and we've done $2 billion.
Anyone can donate to the Book of Mormon fund, to print Books of Mormon in virtually every language.
Anyone can donate to the Missionary Fund, to help with the costs of going on Missions to preach the LDS gospel full time.
I don't remember any more.