Does anyone know of a similar tool as phpmyadmin for sqlserver ? Especially the data dump is very handy. But also updating etc, without needing to remotely logon etc. is nice.
Yes, there's the new Database Manager application:
At Mix 2009, Microsoft announced this and demoed it. I haven't used it myself, but the demos were gorgeous, and since it's maintained by Microsoft, it's probably the safest bet.
Weird that no one mentionned myLittleAdmin. This is a 13-year-old project with a robust and stable kernel. Its interface is very similar to SSMS one. And of course it is a full web-based app.
SQL Web Data Administrator may be sufficient for what you're looking to do, but it hasn't been updated in about a year and a half. If you need more info, there's a review by SQL Server MVP Jacob Sebastian on SQL Server Central.
I've certainly looked for one and haven't found anything decent. However, Rob Allen recently said he is going to try to build one for the European WinPHP Challenge 2009, so it might be worth watching.