Is there a requirements/issue tracker software which is similar to Google spreadsheet?

We have Fogbugz but I find it more heavyweight and slow than a simple spreadsheet.

Is there a Fogbugz alternative which is - fast - can show issues/requirements as a spreadsheet (at) and allows in-place editing - supports tree structures (where issue can have child issues)?

It is required for a small project. There will be 2 developers and 1-2 other users. I guess that only one user will be actively maintaining it.

UPDATE

I do not say that a spreadsheet is better than Fogbugz or similar tools. In fact I am looking for a tool which is similar to Fogbugz and could replace a spreadsheet, but faster than Fogbugz and has an additional feature (table-like mode). I'd like to find a tool which can operate in a mode which looks like a table (one row per issue) but has a rich set features (similar to Fogbugs and JIRA).

I find Fogbugz (and similar tools) inconvenient because I must enter the web form in order to edit anything. In-place editing (when issues are shown as a table) would be much faster.