Agree you need a bag (one you can carry the paper manual in as well), and a second SD card right now, and either the AA battery adapter or a second battery. I also am in the 'use a UV filter all the time' camp - there is the other camp that's greatly opposed to their general use. Lenstip did a good test of lots of brands and the Hoya HMC came out best - that's not their most expensive one, it's one up from the cheapest one.
Beyond that, as is said above, it depends on what sort of photography you do.
If you start dabbling in ND filters (graduated or otherwise) look at the Cokin-style systems as one set of P-size filters will do lots of lenses with just an extra adapter ring if they have a different filter ring size, plus you can slide graduated filters up & down to get the graduation in the right place.
I do lots of long exposures so a tripod is a must, but the remote release is a luxury - the shutter delay on the camera is almost as good.
Also - hard disk space on your PC, and a backup. Hard disks of a size unimaginable just a few years back are cheap. Make sure you have plenty of room on your PC for your images, and make sure you have some sort of backup - an external USB HDD will do - and always download your images from the camera every time you use it.
There are all sorts of things you might want in the long term - Photoshop, a fancy monitor for your PC, lots of RAM for the PC, a new PC, a fancy large-format printer, more lenses...
However, hopefully you have got a DSLR as you want to take better images. Better image quality, better artistic merit. It's easy to fine help with the former, help with the later is a lot harder. Some suggestions:
1) Join a Flickr group
Flickr: Photography Critique
2) Join a camera club
3) Take a photography course