Many topics could suit several different categories. Work round the ideas - for example, collecting cards could give you ideas for all kinds of topics: trading cards, playing cards, sports cards, business cards... and DIY tips could mean painting, tiling, gardening or double glazing tips.
Also Self Help type, Entertainment type, Electronics type, Health and Medicine type, Sports - Keeping Fit type, Food type, Finance type, Travel - Vacation Ideas etc can be the topic. I hope you find these website topics useful to spark some ideas.