I've been on my SmugMug trial for a few days now and have uploaded 4 galleries to it, totalling 4.3gb so far. It uploads (on my 6.5mb connection) at a rock-solid 360-368kb/s. I haven't found anything in there I've wanted to do and can't yet. I'm going to try uploading HD videos next.

Thanks again all for your advice. There are lots of similar sites to SmugMug, but I'm well pleased with this one.