When it comes to calcium, I'm abit of a radical. The American government reommends 1000mg of calcium a day. I think that the bar is set artificially high. I've read a lot of conflicting studies, and I would personally say that you need about 600-800mg of calcium a day. (FYI, in the UK, the calcium RDA is set at 900mg AFAI)
I'm not a vegan, but since I have a strong dislike of most dairy products, I can probably tell you where i get my calcium from. There is calcium in beans, notably chickpeas, which I eat a fair few of. Tahini is a good source of calcium, but I rarely eat tahini.
I just drink fortified juice every now and then. And I have the occasional pizza (w/ cheese) so that's a source of calcium, i guess.
Personally, i don't worry about calcium all that much. I just get a fortified juice drink every couple of days and drink it. In one litre, there's about 1200mg of calcium, so one can last about two days as I see it.