sync

how to synchronize two computers? below are some ways when only one computer is used at a time (eg one is mainly used in office, the other elsewhere):

for documents/files that i use very often, i put them in a dropbox folder; dropbox is free and convenient to use, but it can only hold up to 2gb of data unless you pay for the extra space. also, if you move a file out of the folder, it will be removed from the dropbox folder on other machines; therefore, to keep files synchronized, they have to be in the dropbox folder.

for emails, it's very difficult to sync. the best way seems to be just using gmail or any other web-based mail services. it's possible to upload all the mails from programs such as thunderbird or mail to gmail, using the latter's imap capability.

for bookmarks, xmarks is easy to use and is free. the basic idea is like dropbox -- storing the bookmarks on the cloud. or wait for firefox 4, which has a built-in bookmark syncing capability.

for all other files, i think rsync is the most convenient way. you can set up ssh so that no password/pass phrase is required to login from one computer to another -- this saves a lot of typing whenever you do rsync! furthermore, rsync is fast, scriptable (see eg this article) and easy to customize, and has the ability to do a dry run (ie only showing what will be sync'ed without actually syncing). i found it much easier than using unison.