I use Ubuntu 10.10. When I have a lot of windows open, it's hard to read them in the taskbar because there's only room for a few characters of each window's title.
How can I increase the number of rows available, like in Windows?
You just need to make the panel higher. It will automatically use more rows.
Right click on some empty space in the panel, click on properties and select a bigger size, like 48 pixels.
The default setting on mine is 24, if you increase it to 48, I can have a double layer task bar, and so on.
One thing you might notice is on some window themes, they don't like double size panels and so you might get a stripe down the middle of it. In some window themes you don't get it. e.g. in Equinox Ambient (which is what I'm running at the moment) you get the strange stripe, in New Wave you don't (see below).
Single layer panel:
Double panel with artefact (Equinox theme)
Double panel without artefact (New Wave theme)