FlowLayout from http://nishantvnair.wordpress.com/2010/09/28/flowlayout-in-android/ ported to c#/Mono for Android

FlowLayout.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using Android.App;
using Android.Content;
using Android.OS;
using Android.Runtime;
using Android.Util;
using Android.Views;
using Android.Widget;

namespace Bzing.Client.Droid.UserControls
{
    public class FlowLayout : ViewGroup
    {
        private int line_height;

        public class LayoutParams : ViewGroup.LayoutParams
        {
            public readonly int horizontal_spacing;
            public readonly int vertical_spacing;

            /**
             * @param horizontal_spacing Pixels between items, horizontally
             * @param vertical_spacing Pixels between items, vertically
             */
            public LayoutParams(int horizontalSpacing, int verticalSpacing)
                : base(0, 0)
            {
                this.horizontal_spacing = horizontalSpacing;
                this.vertical_spacing = verticalSpacing;
            }
        }

        public FlowLayout(Context context, IAttributeSet attrs) :
            base(context, attrs)
        {
            Initialize();
        } 

        private void Initialize()
        {
        }


        protected override void OnMeasure(int widthMeasureSpec, int heightMeasureSpec)
        {
            //assert (MeasureSpec.getMode(widthMeasureSpec) != MeasureSpec.UNSPECIFIED);

            int width = MeasureSpec.GetSize(widthMeasureSpec) - PaddingLeft - PaddingRight;
            int height = MeasureSpec.GetSize(heightMeasureSpec) - PaddingTop - PaddingBottom;
            int count = ChildCount;
            int line_height = 0;

            int xpos = PaddingLeft;
            int ypos = PaddingTop;

            int childHeightMeasureSpec;
            if (MeasureSpec.GetMode(heightMeasureSpec) == MeasureSpecMode.AtMost)
            {
                childHeightMeasureSpec = MeasureSpec.MakeMeasureSpec(height, MeasureSpecMode.AtMost);
            }
            else
            {
                childHeightMeasureSpec = MeasureSpec.MakeMeasureSpec(0, MeasureSpecMode.Unspecified);
            }

            for (int i = 0; i < count; i++)
            {
                View child = GetChildAt(i);
                if (child.Visibility != ViewStates.Gone)
                {
                    LayoutParams lp = (LayoutParams)child.LayoutParameters;
                    child.Measure(MeasureSpec.MakeMeasureSpec(width, MeasureSpecMode.AtMost), childHeightMeasureSpec);
                    int childw = child.MeasuredWidth;
                    line_height = Math.Max(line_height, child.MeasuredHeight + lp.vertical_spacing);

                    if (xpos + childw > width)
                    {
                        xpos = PaddingLeft;
                        ypos += line_height;
                    }

                    xpos += childw + lp.horizontal_spacing;
                }
            }
            this.line_height = line_height;

            if (MeasureSpec.GetMode(heightMeasureSpec) == MeasureSpecMode.Unspecified)
            {
                height = ypos + line_height;

            }
            else if (MeasureSpec.GetMode(heightMeasureSpec) == MeasureSpecMode.AtMost)
            {
                if (ypos + line_height < height)
                {
                    height = ypos + line_height;
                }
            }

            SetMeasuredDimension(width, height);
        }

        protected override ViewGroup.LayoutParams GenerateDefaultLayoutParams()
        {
            return new LayoutParams(1, 1); // default of 1px spacing
        }

        protected override bool CheckLayoutParams(ViewGroup.LayoutParams p)
        {
            if (p is LayoutParams)
            {
                return true;
            }
            return false;
        }

        protected override void OnLayout(bool changed, int l, int t, int r, int b)
        {
            int count = ChildCount;
            int width = r - l;
            int xpos = PaddingLeft;
            int ypos = PaddingTop;

            for (int i = 0; i < count; i++)
            {
                View child = GetChildAt(i);
                if (child.Visibility != ViewStates.Gone)
                {
                    int childw = child.MeasuredWidth;
                    int childh = child.MeasuredHeight;
                    LayoutParams lp = (LayoutParams)child.LayoutParameters;
                    if (xpos + childw > width)
                    {
                        xpos = PaddingLeft;
                        ypos += line_height;
                    }
                    child.Layout(xpos, ypos, xpos + childw, ypos + childh);
                    xpos += childw + lp.horizontal_spacing;
                }
            }
        }
    }
}