Should I buy a Nokia n810? I had a nokia n770, and i didnt really get to use it. I could buy one for $70, but there are other things I want.

What do you want to use it for? The price looks good, and if I didn't have several already I'd get it, but without knowing your circumstances it's hard to say if it's a worthwhile purchase for you or not.

are you aware the the N810 has not SIM card?
there was no n770; it was the 770.

The N810 is one of the best pocket computers out there, but you get to internal memory full pretty soon unless you move maemo to the memory card. It's a bit slow for todays webpages except if you use opera, and it's not lightning fast there either. But the screen and stylus and small desktop-like controls along with the spacious hardware keyboard make it very usable for content creation, (not just consumption as most of todays tablets). Finally the fact that many desktop transcoders have the N810 video profile preloaded, that it has a kickstand and good stereo speakers make it a good video-watching device.

Particularly if you add a memory card, it makes a good "MP3 player with benefits". Podcasts. Gnumeric for spreadsheets. Opera Mobile for rudimentary browsing. Games. Terminal. Python. Can you get mileage out of that?

Having the N900, I still use the N810 frequently. As qwazix & buurmas said if you buy it, install a memory card. The first thing I did was to install Easy Debian, you can have with it utils like Open Office or Gimp, but they are slower than on the N900. Still very cool.

The 4.13 inches screen is good for watching videos, the HW keyboard is great. For browsing I've found it good even today, no problems for Facebook, or other webpages except the sites using the most recent versions of Flash. You can have Opera too; as for games there are ports of classic games like Quake (id Software), Shadow Warrior (3D Realms), etc.

It connects fast to Wi-Fi; battery life is decent; I use it basically for browsing and IRC with XChat.

You don't need it, you want it. Is What You Need or what you want most important? YEAH, THATS RIGHT... Get it!