Does the synced blockchain always grow in size?
The Bitcoin.org client v0.7 and lower will continuously increase in size about once every ten minutes, on average.

Blockchain.info provides a chart showing the size of the data (actual disk consumption will be slightly larger even.)

The Bitcoin.org client v0.8, being developed now, dramatically changes how it stores and accesses data that will reduce the amount of disk storage space to some degree but also will provide a dramatic increase in performance.